To identify common regions of deletion in human bladder tumors, we have screened 83 cases of transitional cell carcinoma for loss of heterozygosity (LOH) on all autosomal chromosome arms. Seventy-two restriction fragment length polymorphism, variable number of tandem repeats, and minisatellite markers and 18 microsatellite markers were used to obtain a minimum of 50% informative results for each chromosome arm. A mean of 29.6 informative results per patient was obtained from 39 chromosome arms studied, representing information for 76% of chromosome arms. The most frequent losses were apparent monosomies of chromosome 9 (9p, 51%; 9q, 57%). Other frequent losses were on chromosomes 11p (32%), 17p (32%), 8p (23%), 4p (22%), and 13q (15%). LOH of 4p has not been reported previously in bladder carcinoma. The frequency of LOH on all other chromosome arms was < 12%. LOH on chromosome 8p showed a significant association with both high tumor grade and stage, and LOH on 13q showed a significant association with high tumor grade. Fractional allelic loss was calculated for all tumors and had a mean of 0.125 and a median of 0.110. A significant association was found between increased fractional allelic loss and higher tumor grade. An association was also found between LOH of chromosomes 8p and 9q and values for fractional allelic loss > or = the median value. No associations were found between LOH on different pairs of chromosome arms.