The efficacy and targeting cells of angiogenesis inhibitor TNP-470 on human squamous cell nasopharyngeal carcinoma (NPC) were investigated. The colorimetric MTT assay was used to evaluate the IC50 values of NPC/HK1 cells and human dermal microvascular endothelial cells (HDMEC) for TNP-470. An NPC human tumor model was built by tumor-bearing nude mice using the NPC cell line of NPC/HK1. TNP-470 (30 mg/kg s.c.) was injected every other day. The results showed that the IC50 of NPC/HK1 cells for TNP-470 was 3.8 times higher than that of HDMEC. A significant difference in tumor volume between control and treatment groups was found after 7 days of treatment and increased thereafter. At the end of the treatment, tumor volume was 773.7 +/- 287.1 mm3 (n = 8) in the control group versus 454.5 +/- 132.8 mm3 (n = 8) in the treatment group (p = 0. 013); the ratio of the mean tumor volume in treated animals to that of control animals was 0.587, resulting a 41.3% decrease in tumor growth. The necrotic area was larger in the treatment group. Physical toxicity did not result from the treatment. These studies suggest that angiogenesis inhibitor TNP-470 is effective in the treatment of squamous cell NPC without obvious toxicity.