On the basis of data gathered from long term residents of 3 widely separated regions of Queensland a multivariate analysis has been made to determine the influence of a number of factors in the aetiology of skin cancer and solar keratosis. Factors considered were age, sex, susceptibility to sunburn, complexion, eye colour, ancestry, occupation, clothing habits and residential district. For both sexes, both diseases and all age groups the factor "susceptibility to sunburn" proved to be the most powerful single discriminant. On the whole it appeared that the genetically based factors as a group provided more information on susceptibility than the environmental factors. The relative importance of "occupation" remains in some doubt. In the tropical area away from the coast it appears to be of considerable importance. In coastal areas its influence appears to be blunted, presumably by factors such as sports and recreation habits.