AbstractBy means of G‐banding techniques, chromosome aberrations were studied in short‐term cultures of normal renal parenchymal cells from 45 patients with renal cell carcinoma. Clonal chromosomal aberrations were detected in 29 patients; loss of the Y chromosome as well as trisomy X, 5, 7, 9, 10, 12, and 18 was found. Chromosomes 7 and 10 were involved preferentially. Results of fluorescence in situ hybridization with chromosome 7‐ and 10‐specific DNA probes on non‐cultured normal kidney cells suggested that the aberrations develope