The stemline chromosome number is hypotetraploid, with the 2S component occurring at 4.4%. Marker chromosomes 1p, t(1q;11q); 11q+; t(13;?); 16q+; t(12q; 18q); M10; t(2q;13q); i(15); and ?t(xp;21q) occurred in all S metaphases, and t(1p;?); t(1p;14q); t(16;?), and t(14;21) occurred in some. In addition, 4 to 9 small markers of unidentifiable origin occurred frequently. Chromosome No. 7 was generally hexasomic, X chromosomes were disomic, and normal No. 15 was absent. No Y chromosome was detected in the QM stained preparation.