The aim of the present study was formulate and clinically evaluate 5-fluorouracil (5-FU) transdermal patches. Cytotoxicity was measured by exposing cell suspensions to increasing concentrations of drug from 10-100 microg/ml and performing viable cell counts by the trypan blue exclusion method. Results confirmed 100 infinity g/ml and 50 microg/ ml of 5-FU to be cytotoxic to EAC and DLA cells. In mice, increase in the life span (ILS) by 87.1% with a maximum survival time of 30.5+/-1.87 days was found with EAC cell-induced tumors, with an ILS of 88.1% and a maximum survival time of 39.5+/-1.87 days for DLA cell-induced lesions with 5-FU transdermal patches. The results were statistically significant (p<0.01) compared to untreated controls. Pharmacokinetic studies in rabbits showed a t1/2 of 29+/-6 min, a Cmax (ng/ml) of 978.23, an AUC0-infinity (ng/ml/h) of 1213.73 +/-14 and a Tmax (h) of 0.5. 5-FU from transdermal patches exhibited a half-life of 95+/-0.5 min, a Cmax (ng/ml) of 863.25, an AUC0-infinity (ng/ml/h) of 1567+/-36 and a Tmax (h) of 1.5. Velcro protection jackets proved suitable in this study to stop mice licking, scratching and rubbing applied patches.