diff --git a/src/net_processing.cpp b/src/net_processing.cpp
--- a/src/net_processing.cpp
+++ b/src/net_processing.cpp
@@ -3432,6 +3432,20 @@
     return -3;
 };
 
+/**
+ * Decide a response for an Avalanche poll about the given transaction.
+ *
+ * FIXME This function should be expanded to return different vote responses
+ * based on inspection of mempool.
+ *
+ * @param[in]   CTxMemPool The mempool to base our votes on
+ * @param[in]   TxId       The id of the transaction being polled for
+ * @param[out]  uint32_t   Our current vote for the proof
+ */
+static uint32_t getAvalancheVoteForTx(CTxMemPool &mempool, const TxId &id) {
+    return -1;
+};
+
 /**
  * Decide a response for an Avalanche poll about the given proof.
  *
@@ -5064,6 +5078,9 @@
 
             // If inv's type is known, get a vote for its hash
             switch (inv.type) {
+                case MSG_TX: {
+                    vote = getAvalancheVoteForTx(m_mempool, TxId(inv.hash));
+                } break;
                 case MSG_BLOCK: {
                     vote = WITH_LOCK(cs_main, return getAvalancheVoteForBlock(
                                                   BlockHash(inv.hash)));
diff --git a/test/functional/abc_p2p_avalanche_transaction_voting.py b/test/functional/abc_p2p_avalanche_transaction_voting.py
new file mode 100755
--- /dev/null
+++ b/test/functional/abc_p2p_avalanche_transaction_voting.py
@@ -0,0 +1,70 @@
+#!/usr/bin/env python3
+# Copyright (c) 2022 The Bitcoin developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+"""Test avalanche transaction polling."""
+import random
+
+from test_framework.avatools import get_ava_p2p_interface
+from test_framework.key import ECPubKey
+from test_framework.messages import MSG_TX, AvalancheVote, AvalancheVoteError
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.util import assert_equal
+from test_framework.wallet import MiniWallet
+
+
+class AvalancheTransactionVotingTest(BitcoinTestFramework):
+    def set_test_params(self):
+        self.num_nodes = 1
+        self.extra_args = [['-enableavalanche=1']]
+
+    def run_test(self):
+        node = self.nodes[0]
+        poll_node = get_ava_p2p_interface(node)
+
+        # Create helper to check expected poll responses
+        avakey = ECPubKey()
+        avakey.set(bytes.fromhex(node.getavalanchekey()))
+
+        def assert_response(expected):
+            response = poll_node.wait_for_avaresponse()
+            r = response.response
+
+            # Verify signature.
+            assert avakey.verify_schnorr(response.sig, r.get_hash())
+
+            # Verify correct votes list
+            votes = r.votes
+            assert_equal(len(votes), len(expected))
+            for i in range(0, len(votes)):
+                assert_equal(repr(votes[i]), repr(expected[i]))
+
+        # Create random non-existing tx ids and poll for them
+        tx_ids = [random.randint(0, 2**256) for _ in range(10)]
+        poll_node.send_poll(tx_ids, MSG_TX)
+
+        # Each tx id should get an UNKNOWN response
+        assert_response(
+            [AvalancheVote(AvalancheVoteError.UNKNOWN, id) for id in tx_ids])
+
+        # Make real txs
+        num_txs = 5
+        wallet = MiniWallet(node)
+        wallet.generate(num_txs)
+
+        # Mature the coinbases
+        node.generate(100)
+
+        assert_equal(node.getmempoolinfo()['size'], 0)
+        tx_ids = [int(wallet.send_self_transfer(from_node=node)
+                      ['txid'], 16) for _ in range(num_txs)]
+        assert_equal(node.getmempoolinfo()['size'], num_txs)
+
+        # These real txs are also voted as UNKNOWN for now
+        poll_node.send_poll(tx_ids, MSG_TX)
+        assert_response(
+            [AvalancheVote(AvalancheVoteError.UNKNOWN, id) for id in tx_ids])
+
+
+if __name__ == '__main__':
+    AvalancheTransactionVotingTest().main()