Angiogenesis is now known to play an important role in both growth and metastasis of lung cancer. The intense interest in angiogenesis has led to it re-examination of the activity of many established cytotoxic agents. Some results of recent experimental studies have suggested that frequent administration of certain cytotoxic agents at low doses increases the antiangiogenic activity of the drugs. In the present study, we investigated the efficacy of the combination of low-dose cyclophosphamide and ginsenoside Rg3 for the antiangiogenic effect on Lewis lung carcinoma. Our findings suggest that continuous low-dose regimen of CTX increases the efficacy of targeting the tumor microvasculature, which produces therapeutic activity with decreased toxicity. The effects of the low-dose schedule of CTX may be further enhanced by concurrent administration of angiogenic inhibitor ginsenoside Rg3. As an antiangiogenic method, this regimen has the advantage of a reduced susceptibility to drug resistance mechanisms and improved animal survival. (c) 2006 Elsevier Inc. All rights reserved.