BACKGROUND Breast cancer is the main type of cancer in women, and triple-negative breast cancer (TNBC) is a unique subtype of breast cancer. The expression of miR-940 has been shown to play an important role in various cancers; however, the role of miR-940 in TNBC remains unknown. MATERIAL AND METHODS The expression of miR-940 in TNBC tissues or cells were tested by qRT-PCR; the expression of miR-940 in cells were overexpressed by miR-940 mimics, and suppressed by anti-miR-940. Bioinformatics algorithms from TargetScanHuman were used to predict the target genes of miR-940. The interaction between miR-940 and ZNF24 was confirmed by dual luciferase assays. The protein level was assayed by Western blot. RESULTS TNBC tissues and cells showed lower miR-940 levels. CONCLUSIONS MiR-940 inhibited cellular proliferation and migration in TNBC.