A retrospective, population-based study was conducted to evaluate the incidence, clinical features, and outcome of malignancy-associated hemophagocytic lymphohistiocytosis (M-HLH) in adults. Between January 1996 and December 2009, eight out of 887 (0.9%) patients diagnosed with hematological malignancies developed aggressive M-HLH in an area inhabited by approximately 160,000 people. Thus the estimated annual incidence of M-HLH in adulthood was 0.36/100,000 individuals/year. The clinical course of M-HLH was aggressive in all patients. Six patients were treated with a modified HLH-94 protocol; three achieved remission (durable in one case) while the others did not respond and died within an average of 2.4 months (range 1.5-3.5) after M-HLH diagnosis. Infection complicating the course of M-HLH occurred in four (50%) patients, all of whom developed fulminant M-HLH and died. Although the small study population limits the results, the long observation period strengthens its value.