diff --git a/tests/bugs/gh_7903_test.py b/tests/bugs/gh_7903_test.py
new file mode 100644
index 00000000..e5f892c5
--- /dev/null
+++ b/tests/bugs/gh_7903_test.py
@@ -0,0 +1,89 @@
+#coding:utf-8
+
+"""
+ID:          issue-7903
+ISSUE:       https://github.com/FirebirdSQL/firebird/issues/7903
+TITLE:       Unexpected Results when Using CASE-WHEN with LEFT JOIN
+DESCRIPTION:
+NOTES:
+    [04.12.2023] pzotov
+    Confirmed bug on 6.0.0.139
+    Checked on 6.0.0.169, 5.0.0.1292
+"""
+
+import pytest
+from firebird.qa import *
+
+db = db_factory()
+
+test_script = """
+    recreate table t0(id int, a int);
+    recreate table t1(id int, b int);
+
+    insert into t0(id) values (1);
+
+    set count on;
+    set list on;
+
+    select 'case-1a' as msg, t0.*, t1.* from t0 natural left join t1 where case 1 when t1.id then false else true end;
+    select 'case-1b' as msg, t0.*, t1.* from t0 natural left join t1 where case t1.id when 1 then false else true end;
+
+    select 'case-2a' as msg, t0.*, t1.* from t0 left join t1 using(id) where case 1 when t1.id then false else true end;
+    select 'case-2b' as msg, t0.*, t1.* from t0 left join t1 using(id) where case t1.id when 1 then false else true end;
+
+    select 'case-3a' as msg, t0.*, t1.* from t0 left join t1 on t0.id = t1.id where case 1 when t1.id then false else true end;
+    select 'case-3b' as msg, t0.*, t1.* from t0 left join t1 on t0.id = t1.id where case t1.id when 1 then false else true end;
+
+"""
+
+act = isql_act('db', test_script)
+
+expected_stdout = """
+    MSG                             case-1a
+    ID                              1
+    A                               <null>
+    ID                              <null>
+    B                               <null>
+    Records affected: 1
+
+    MSG                             case-1b
+    ID                              1
+    A                               <null>
+    ID                              <null>
+    B                               <null>
+    Records affected: 1
+
+    MSG                             case-2a
+    ID                              1
+    A                               <null>
+    ID                              <null>
+    B                               <null>
+    Records affected: 1
+
+    MSG                             case-2b
+    ID                              1
+    A                               <null>
+    ID                              <null>
+    B                               <null>
+    Records affected: 1
+
+    MSG                             case-3a
+    ID                              1
+    A                               <null>
+    ID                              <null>
+    B                               <null>
+    Records affected: 1
+
+    MSG                             case-3b
+    ID                              1
+    A                               <null>
+    ID                              <null>
+    B                               <null>
+    Records affected: 1
+"""
+
+@pytest.mark.version('>=5.0')
+def test_1(act: Action):
+    act.expected_stdout = expected_stdout
+    act.execute(combine_output = True)
+    assert act.clean_stdout == act.clean_expected_stdout