In the present studies, the effect of Solanum lycopersicum extract on DMBA induced skin papillomas and B6F10 melanomas was studied. Topical single application of DMBA at the dose of 4 mg/kg b.wt. followed by 1 %croton oil for 16 weeks produced a 100% incidence of skin papillomas which started appearing from the 6thweek onwards. The mice which additionally received S. lycopersicum extract at 0.6 g/kg 2 day/week for 16 weeksshowed a significant decrease in the number and incidence of tumors (p< 0.05), with a delay in their appearanceto week 10. Histopathological examination showed well and poorly differentiated squamous cell carcinomas inthe group which received DMBA + Croton oil treatment whereas hyperkeratosis and hyperplasia were moreprevalent in DMBA + Croton oil + Lycopersicum extract treated animals. In a second experiment the effect ofcyclophosphamide alone and in combination with S. lycopersicum extract was studied in B16F10 melanomatumour bearing mice. The inhibition rate was 25.9% in the cyclophosphamide treated group but this increasedto 37.7%with S. lycopersicum. The life span of tumour bearing animals was also increased. Thus in two models,S. lycopersicum extract exerted protective potential against skin tumors.