171 episodes of bacteremia and candidemia in 142 patients were recorded during the period 1981-1985 in patients with hematological malignancies. Overall mortality, within 1 week of onset of bacteremia, was 20%. Increased mortality was found in patients with poor disease-prognosis (39%), with granulocytopenia for more than 6 days (30%), and in those developing hypotension (49%). Compared to a similar previous study from 1970-1974, the incidence of bacteremia remained unchanged, but the mortality had decreased by 50%. This result could not be explained by changes in microbial spectrum, in patient groups, or in the initial antibiotic regimen used. An improved general condition of these patients due to better supportive treatment may be the single most important factor in improving the outcome of septicemia.