diff --git a/seqBackupLib/backup.py b/seqBackupLib/backup.py
index f9745a0..56fd0d7 100644
--- a/seqBackupLib/backup.py
+++ b/seqBackupLib/backup.py
@@ -41,6 +41,14 @@ def return_md5(fp: Path) -> str:
     return hash_md5.hexdigest()
 
 
+def check_backup(forward_reads: Path, dest_dir: Path) -> bool:
+    with gzip.open(forward_reads, mode="rt") as f:
+        r1 = IlluminaFastq(f)
+        archive_dir = dest_dir / r1.build_archive_dir()
+        md5_fp = archive_dir / f"{r1.build_archive_dir()}.md5"
+    return archive_dir.is_dir() and md5_fp.is_file()
+
+
 def backup_fastq(
     forward_reads: Path,
     dest_dir: Path,
@@ -144,7 +152,14 @@ def main(argv=None):
         default=DEFAULT_MIN_FILE_SIZE,
         help="Minimum file size to register in bytes",
     )
+    parser.add_argument(
+        "--check",
+        action="store_true",
+        help="Check if the target directory and md5 file exist without backing up",
+    )
     args = parser.parse_args(argv)
+    if args.check:
+        return check_backup(args.forward_reads, args.destination_dir)
     return backup_fastq(
         args.forward_reads,
         args.destination_dir,
diff --git a/test/test_backup.py b/test/test_backup.py
index b571898..75c07c6 100644
--- a/test/test_backup.py
+++ b/test/test_backup.py
@@ -132,3 +132,34 @@ def test_main_returns_archive_path(tmp_path, full_miseq_dir):
     expected_dir = raw / "250407_M03543_0443_000000000-DTHBL_L001"
     assert out_dir == expected_dir
     assert expected_dir.is_dir()
+
+
+def test_main_check(tmp_path, full_miseq_dir):
+    raw = tmp_path / "raw_reads"
+    raw.mkdir(parents=True, exist_ok=True)
+    sample_sheet_fp = full_miseq_dir / "sample_sheet.csv"
+
+    base_args = [
+        "--forward-reads",
+        str(full_miseq_dir / "Undetermined_S0_L001_R1_001.fastq.gz"),
+        "--destination-dir",
+        str(raw),
+        "--sample-sheet",
+        str(sample_sheet_fp),
+        "--min-file-size",
+        "100",
+    ]
+
+    assert not main(base_args + ["--check"])
+
+    main(base_args)
+
+    assert main(base_args + ["--check"])
+
+    md5_fp = (
+        raw
+        / "250407_M03543_0443_000000000-DTHBL_L001"
+        / "250407_M03543_0443_000000000-DTHBL_L001.md5"
+    )
+    md5_fp.unlink()
+    assert not main(base_args + ["--check"])