Cytogenetic diagnosis of leukemia was taken into use at the Norwegian Radium Hospital in late 1988. The article presents results from the period 1989-90. The samples arrived the laboratory on the same day they were obtained from the patients, and the results indicate that the transport had no effect on outcome. The success rate (obtained by cytogenetic diagnosis) was 82%. Among the persons who were diagnosed successfully, 66% showed clonal abnormalities. Diagnostic and prognostic implications are discussed.