OBJECTIVE To investigate the effectiveness of (131)I-epidermal growth factor (EGF) on the proliferation of a heterologous graft in nude mice bearing human breast infiltrating duct carcinoma. METHODS EGF/HAS was labeled with (131)I by chloramines-T method. Human breast cancer xenografts with positive EGFR expression were established in nude mice. The nude mice were injected with normal saline, Epirubicin Hydrochloride, (131)I-EGF, (131)I-HAS, (131)I intravenously and (131)I-EGF intratumoral administration respectively. The tumor growth inhibition rate was determined by measurement of tumor volume. Different examinations were carried out. RESULTS There was remarkable significant difference of tumor volumes at 26th day among (131)I-EGF trial groups, (131)I, (131)I-HAS, and the negative control group. The tumor growth inhibition rate of (131)I-EGF trial groups was 82.0%, 80.7% respectively. Compared with the negative control group, the (131)I-EGF trial groups remarkably suppressed the growth of tumor (P < 0.05). Irreversible destruction of tissues in (131)I-EGF groups was observed under light and electron microscope. There was no evidence of hepatotoxicity, renal toxicity and myelotoxicity in nude mice bearing human breast cancer given (131)I-EGF over a 4-wk observation period. CONCLUSION (131)I-EGF has obvious antitumor effects on a heterologous graft in nude mice bearing human breast infiltrating duct carcinoma, with little obvious side effects.