One-hundred-and-thirty typical, unselected CLL cases were studied by conventional cytogenetic analysis. Seventy-three patients (56.2%) had normal karyotype ('normal sub-group'), while 57/130 patients (43.8%) had abnormal karyotype. Twenty-two of 57 patients (38.6%) carried more than one abnormality. Six novel chromosomal abnormalities were detected in five patients: (i) t(3;13)(q14;q34); (ii) t(Y;11)(q12;q23), del(13)(q12q14); (iii) dic(3;11)(p21;q23); (iv) t(3;5)(q29;q23); (v) t(3;22) (p21;q13); and (vi) t(1;13)(p12;q12). Three of five patients carrying novel translocations had progressive disease. The true biological and clinical significance of novel chromosomal abnormalities remains to be determined.