Squamous cell carcinomas of the nasal floor present problems for surgical therapy. Similarly, basal cell carcinoma of the nasal floor and alae requires extensive reconstruction when cures are obtained. To improve the results, we have treated the squamous cell carcinomas with topical 5-fluorouracil to obtain sensitization and shrinkage of the tumor before resection. The same has been done with basal cell carcinomas, but in selected patients the topical 5-fluorouracil has been continued until biopsies are negative. Thus, the costs of resection and reconstruction have been avoided and excellent cosmetic results are possible. This treatment is lengthy and requires weekly supervision. It offers a different approach that gives surgeons further options in treating these difficult carcinomas in carefully selected and cooperative patients.