diff --git a/rs/nns/governance/src/neuron/types.rs b/rs/nns/governance/src/neuron/types.rs
index 59c7a3e2042..276fbdd246d 100644
--- a/rs/nns/governance/src/neuron/types.rs
+++ b/rs/nns/governance/src/neuron/types.rs
@@ -1358,6 +1358,7 @@ impl Neuron {
         let deciding_voting_power =
             Some(self.deciding_voting_power(voting_power_economics, now_seconds));
         let potential_voting_power = Some(self.potential_voting_power(now_seconds));
+        let recent_ballots = self.sorted_recent_ballots();
 
         let Neuron {
             id,
@@ -1370,7 +1371,7 @@ impl Neuron {
             created_timestamp_seconds,
             spawn_at_timestamp_seconds,
             followees,
-            recent_ballots,
+            recent_ballots: _,
             kyc_verified,
             transfer,
             maturity_e8s_equivalent,
diff --git a/rs/nns/governance/src/neuron/types/tests.rs b/rs/nns/governance/src/neuron/types/tests.rs
index a9e0ca3c0af..804dfc0d2e6 100644
--- a/rs/nns/governance/src/neuron/types/tests.rs
+++ b/rs/nns/governance/src/neuron/types/tests.rs
@@ -10,14 +10,130 @@ use crate::{
     temporarily_enable_private_neuron_enforcement, temporarily_enable_voting_power_adjustment,
 };
 use ic_cdk::println;
-
 use ic_nervous_system_common::{E8, ONE_MONTH_SECONDS, ONE_YEAR_SECONDS};
 use icp_ledger::Subaccount;
+use maplit::hashmap;
+use pretty_assertions::assert_eq;
 
 const NOW: u64 = 123_456_789;
 
 const TWELVE_MONTHS_SECONDS: u64 = 30 * 12 * 24 * 60 * 60;
 
+/// Our main goal here is to make sure that recent_ballots is populated
+/// correctly.
+#[test]
+fn test_neuron_into_api() {
+    // Step 1: Prepare "the world". In this case, that just consists of
+    // constructing a native Neuron.
+
+    let some_timestamp_seconds = 1738239721;
+
+    let dissolve_state_and_age = DissolveStateAndAge::NotDissolving {
+        dissolve_delay_seconds: 100,
+        aging_since_timestamp_seconds: some_timestamp_seconds + 30,
+    };
+
+    let mut original_neuron = NeuronBuilder::new(
+        NeuronId { id: 7 },
+        Subaccount::try_from(vec![8_u8; 32].as_slice()).unwrap(),
+        PrincipalId::new_user_test_id(9),
+        dissolve_state_and_age,
+        some_timestamp_seconds + 3, // created_timestamp_seconds
+    )
+    .build();
+
+    // Add ballots.
+    for i in 0..10 {
+        let proposal_id = Some(ProposalId { id: 123_000 + i });
+
+        original_neuron.recent_ballots.push(pb::BallotInfo {
+            proposal_id,
+            vote: Vote::No as i32,
+        });
+    };
+    original_neuron.recent_ballots_next_entry_index = Some(3);
+
+    // Step 2: run code under test.
+    let api_neuron = original_neuron.clone().into_api(some_timestamp_seconds + 99, &VotingPowerEconomics::DEFAULT);
+
+    // Step 3: Inspect result(s).
+
+    // Survives round trip.
+    assert_eq!(
+        Neuron {
+            // This is checked separately.
+            recent_ballots: vec![],
+            ..Neuron::try_from(api_neuron.clone()).unwrap()
+        },
+        Neuron {
+            recent_ballots: vec![],
+            recent_ballots_next_entry_index: None,
+            visibility: Some(pb::Visibility::Private),
+            ..original_neuron.clone()
+        }
+    );
+
+    // Verify most fields, or at least, the interesting ones.
+    let potential_voting_power = Some(original_neuron.potential_voting_power(some_timestamp_seconds + 99));
+    let deciding_voting_power = Some(original_neuron.deciding_voting_power(&VotingPowerEconomics::DEFAULT, some_timestamp_seconds + 99));
+    assert_eq!(
+        api::Neuron {
+            recent_ballots: vec![],
+            ..api_neuron.clone()
+        },
+        api::Neuron {
+            // Fields with "interesting" values.
+            id: Some(NeuronId { id: 7 }),
+            account: vec![8_u8; 32],
+            controller: Some(PrincipalId::new_user_test_id(9)),
+            dissolve_state: Some(api::neuron::DissolveState::DissolveDelaySeconds(100)),
+            aging_since_timestamp_seconds: some_timestamp_seconds + 30,
+            created_timestamp_seconds: some_timestamp_seconds + 3,
+            visibility: Some(Visibility::Private as i32),
+            voting_power_refreshed_timestamp_seconds: Some(some_timestamp_seconds + 3),
+
+            // Other fields have default value.
+            hot_keys: vec![],
+            cached_neuron_stake_e8s: 0,
+            neuron_fees_e8s: 0,
+            spawn_at_timestamp_seconds: None,
+            followees: hashmap!{},
+            recent_ballots: vec![],
+            kyc_verified: false,
+            transfer: None,
+            maturity_e8s_equivalent: 0,
+            staked_maturity_e8s_equivalent: None,
+            auto_stake_maturity: None,
+            not_for_profit: false,
+            joined_community_fund_timestamp_seconds: None,
+            known_neuron_data: None,
+            neuron_type: None,
+            potential_voting_power,
+            deciding_voting_power,
+        },
+    );
+
+    // In particular, recent_ballots_next_entry_index is used (indirectly) during conversion.
+    let expected_proposal_ids = vec![
+        123_002, 123_001, 123_000, 123_009, 123_008, 123_007, 123_006, 123_005, 123_004, 123_003,
+    ];
+    assert_eq!(expected_proposal_ids.len(), 10);
+    assert_eq!(
+        api_neuron.recent_ballots,
+        expected_proposal_ids
+            .into_iter()
+            .map(|id| {
+                let proposal_id = Some(ProposalId { id });
+
+                api::BallotInfo {
+                    proposal_id,
+                    vote: Vote::No as i32,
+                }
+            })
+            .collect::<Vec<_>>(),
+    );
+}
+
 #[test]
 fn test_dissolve_state_and_age_conversion() {
     let test_cases = vec![