Long survival in B‐CLL correlates with surface IgMK phenotype

200 patients with B-cell chronic lymphocytic leukaemia (B-CLL) presenting to a single centre over 13 years have been studied. In 72.2% the diagnosis was made on an incidental blood count, and 70.1% were stage A at presentation. Those patients whose cells expressed surface IgM kappa were significantly more likely to be stage A at presentation and significantly less likely to have a lymphocyte count greater than 50 X 10(9)/l, to have progressive disease or to require treatment than those with other classes of surface Ig. Patients whose cells express surface IgM kappa have a significantly longer actuarial survival than others and this is also so when only patients in Binet stage A or when only patients presenting below the age of 75 are studied. By studying all of the cases presenting in a single catchment area we have attempted to avoid the bias against trivial disease likely to be seen in specialist referral centres.