279 B-CLL patients entered randomized IGCI clinical trial to compare the remission rate and survival of high dose continuous chlorambucil (regimen A) vs intermittent chlorambucil plus prednisone (regimen B), and to assess the effect of early treatment on survival. Regimen A was significantly better for remission induction (p less than 0.001), and prolonged survival (p less than 0.01) in comparison to regimen B. More aggressive chemotherapy is associated with better response but requires close monitoring of both antineoplastic effect and haematological toxicity. Total tumor mass score (TTM) proved to be suitable for definition of both early, stable disease and the response to therapy because of its quantitative continuous character and its independence of bone marrow failure. This system is helpful for the detection of treatment toxicity and consequently enables safe monitoring of therapy. Although statistically significant difference has not yet been reached between the patients treated early and non treated patients the latter group seems to fare better.