We examined 88 nonpapillary renal cell carcinomas for allelic loss at chromosome arm 14q and correlated the results to size, grade, and stage of these tumors. Fourteen highly polymorphic microsatellite markers on the long arm of chromosome 14 were used for deletion mapping. Loss of heterozygosity (LOH) at the smallest overlapping segment of 14q24.2-qter was seen in 42 of 88 tumors. There was no significant correlation between frequency of 14q LOH and size of tumors (P = 0.11). LOH was frequently seen in grade 2 and 3 tumors (55% and 73%, respectively) and in stage III and IV tumors (53% and 80%, respectively). We found a significant correlation between chromosome arm 14q LOH and nuclear grade (P < 0.001) and stage (P < 0.001) of tumors. These observations indicate the presence of a tumor-suppressor gene at chromosome segment 14q24.2-qter and demonstrate the usefulness of microsatellite analysis for assessing the possible clinical outcome of nonpapillary renal cell carcinomas.