diff --git a/test_runner/regress/test_lfc_working_set_approximation.py b/test_runner/regress/test_lfc_working_set_approximation.py
new file mode 100644
index 0000000000..a6f05fe0f7
--- /dev/null
+++ b/test_runner/regress/test_lfc_working_set_approximation.py
@@ -0,0 +1,74 @@
+from pathlib import Path
+
+from fixtures.log_helper import log
+from fixtures.neon_fixtures import NeonEnv
+from fixtures.utils import query_scalar
+
+
+def test_lfc_working_set_approximation(neon_simple_env: NeonEnv):
+    env = neon_simple_env
+
+    cache_dir = Path(env.repo_dir) / "file_cache"
+    cache_dir.mkdir(exist_ok=True)
+
+    branchname = "test_approximate_working_set_size"
+    env.neon_cli.create_branch(branchname, "empty")
+    log.info(f"Creating endopint with 1MB shared_buffers and 64 MB LFC for branch {branchname}")
+    endpoint = env.endpoints.create_start(
+        branchname,
+        config_lines=[
+            "shared_buffers='1MB'",
+            f"neon.file_cache_path='{cache_dir}/file.cache'",
+            "neon.max_file_cache_size='128MB'",
+            "neon.file_cache_size_limit='64MB'",
+        ],
+    )
+
+    cur = endpoint.connect().cursor()
+    cur.execute("create extension neon")
+
+    log.info(f"preparing some data in {endpoint.connstr()}")
+
+    ddl = """
+CREATE TABLE pgbench_accounts (
+    aid bigint NOT NULL,
+    bid integer,
+    abalance integer,
+    filler character(84),
+    -- more web-app like columns
+    text_column_plain TEXT  DEFAULT repeat('NeonIsCool', 5),
+    jsonb_column_extended JSONB  DEFAULT ('{ "tell everyone": [' || repeat('{"Neon": "IsCool"},',9) || ' {"Neon": "IsCool"}]}')::jsonb
+)
+WITH (fillfactor='100');
+"""
+
+    cur.execute(ddl)
+    # prepare index access below
+    cur.execute(
+        "ALTER TABLE ONLY pgbench_accounts ADD CONSTRAINT pgbench_accounts_pkey PRIMARY KEY (aid)"
+    )
+    cur.execute(
+        "insert into pgbench_accounts(aid,bid,abalance,filler) select aid, (aid - 1) / 100000 + 1, 0, '' from generate_series(1, 100000) as aid;"
+    )
+    # ensure correct query plans and stats
+    cur.execute("vacuum ANALYZE pgbench_accounts")
+    # determine table size - working set should approximate table size after sequential scan
+    pages = query_scalar(cur, "SELECT relpages FROM pg_class WHERE relname = 'pgbench_accounts'")
+    log.info(f"pgbench_accounts has {pages} pages, resetting working set to zero")
+    cur.execute("select approximate_working_set_size(true)")
+    cur.execute(
+        'SELECT count(*) FROM pgbench_accounts WHERE abalance > 0 or jsonb_column_extended @> \'{"tell everyone": [{"Neon": "IsCool"}]}\'::jsonb'
+    )
+    # verify working set size after sequential scan matches table size and reset working set for next test
+    blocks = query_scalar(cur, "select approximate_working_set_size(true)")
+    log.info(f"working set size after sequential scan on pgbench_accounts {blocks}")
+    assert pages * 0.8 < blocks < pages * 1.2
+    # run a few point queries with index lookup
+    cur.execute("SELECT abalance FROM pgbench_accounts WHERE aid =   4242")
+    cur.execute("SELECT abalance FROM pgbench_accounts WHERE aid =  54242")
+    cur.execute("SELECT abalance FROM pgbench_accounts WHERE aid = 104242")
+    cur.execute("SELECT abalance FROM pgbench_accounts WHERE aid = 204242")
+    # verify working set size after some index access of a few select pages only
+    blocks = query_scalar(cur, "select approximate_working_set_size(true)")
+    log.info(f"working set size after some index access of a few select pages only {blocks}")
+    assert blocks < 10