The carcinogenicity of smoke condensates to mouse skin prepared from plain cigarettes, small cigars and cigarettes manufactured from cigar tobacco has been compared. A statistically significant increase in mouse skin carcinogenicity has been shown with cigar smoke condensate compared with smoke condensate from either flue-cured or cigar tobacco cigarettes. There was no significant difference in mouse skin carcinogenicity between smoke condensate from cigarettes made of flue-cured tobacco or cigar tobacco. There was no difference in incidence of spontaneous occurring tumours of other organs following application of any of the three condensates. © 1969, The British Empire Cancer Campaign for Research. All rights reserved.