Pingyangmycin (also known as Bleomycin A5) is produced by Streptomyces verticillus var. pingyangensis n.sp., and has anti‑tumor activities against a variety of tumor cells. The aim of the present study was to determine the molecular mechanism(s) underlying the therapeutic effects of pingyangmycin against infantile hemangiomas. Human hemangioma‑derived endothelial cells (HemECs) were treated with pingyangmycin at varying concentrations (100, 200 or 300 µg/ml), and the morphological changes and apoptosis levels were assessed. The gene expression changes were determined by cDNA microarray technology. Transmission electron microscopy examination revealed that the pingyangmycin‑treated HemECs exhibited typical apoptotic characteristics, including chromatin condensation and the formation of apoptotic bodies. Annexin‑V staining demonstrated that pingyangmycin caused a significant and dose‑dependent induction of apoptosis in the HemECs. In the pingyangmycin‑treated HemECs, 4,752 genes demonstrated at least 2‑fold expression changes at the mRNA level. Quantitative polymerase chain reaction confirmed that pingyangmycin significantly upregulated the expression of p53, p53‑induced protein with death domain, Bax, p53 upregulated modulator of apoptosis and p53 inducible gene 3, and downregulated the expression of murine double minute 2. The data demonstrated that the pro‑apoptotic activity of pingyangmycin against infantile hemangiomas involves p53 pathway activation.