MicroRNAs (miRs) are a family of small non-coding RNAs that are 21‑24 nucleotides in length. Decreased expression of hsa‑miR‑125a‑3p is observed in a number of patients with non‑small cell lung cancer; however, it is not clear how this miRNA regulates the growth and invasion of lung tumor cells. The aim of the present study was to identify the function of hsa‑miR‑125a‑3p in the growth and invasion of lung cancer cells. The expression of hsa‑miR‑125a‑3p in the A549, NCI‑H460 and SPCA‑1 lung cancer cell lines was analyzed by reverse transcription‑quantitative polymerase chain reaction and the human bronchiolar epithelium cell line (HBE) was used as a control. The results demonstrated that the expression of hsa‑miR‑125a‑3p was significantly lower in NCI‑H460, A549 and SPCA‑1 cells, compared with that in HBE cells. Overexpression of sense miR‑125a‑3p in the A549 lung cancer cell line inhibited cell proliferation for 5‑7 days (P<0.01), and transfection of antisense miR‑125a‑3p did not suppress the cell growth of the lung cancer cells. In addition, overexpression of miR‑125a‑3p in the NCI‑H460 lung cancer cell line markedly induced cell apoptosis, which was detected by fluorescence‑activated cell sorting with annexin V‑fluorescein isothiocyanate/propidium iodide staining. The results of the Transwell migration assay also revealed that transfection of miR‑125a‑3p resulted in decreased migration of lung cancer tumor cells. The pro‑apoptotic gene p53 expression was detected by western blot analysis. The results revealed that the expression of mouse double minute (MDM)‑2 homolog, the principal cellular antagonist of p53, was decreased and p53 expression was upregulated in sense has‑miR‑125a‑3p transfected A549 cells. This was consistent with that observed in NCI‑H460 cells, suggesting that hsa‑miR‑125a‑3p may be involved in the regulation of the MDM2/p53 signaling pathway in lung cancer cells. In conclusion, overexpression of hsa‑miR‑125a‑3p significantly inhibited the proliferation and invasion of lung cancer cells, which may aid in determining the mechanisms underlying the development of lung cancer.