Hemophagocytic syndrome is a severe condition of excessive immune activation that has a high mortality in the absence of treatment. The syndrome is classified as primary if associated with congenital or hereditary problems, or secondary/acquired if associated with infectious, autoimmune or oncology diseases. We report four adult cases of the syndrome, one with viral, two with autoimmune and one with idiopathic causes who were successfully treated with HLH 94-04 chemotherapy protocol. Our experience shows that a high index of suspicion, early diagnosis and an opportune therapy are essential in the treatment of this disease.