Chromosome studies were performed on an adrenocortical carcinoma extending into the kidney. The following karyotype was present in all metaphases: 46,XX,t(4;11)(q35;p13). Two metaphases with an additional del(1)(q23) were found. The results are briefly discussed in relation to specific karyotypic changes in cancer, in general, and to those of adrenocortical tumors, in particular.