An epidemic of an infection associated with circulating hemophagocytes (HP) and activated monocytes (AM) was seen in Bombay. Although certain features overlapped with the well-defined entity of virus-associated hemophagocytic syndrome and familial hemophagocytic lymphohistiocytosis, it was distinct enough to place it in a separate category. Affected children were predominantly two days to two years of age. They had fever, altered sensorium, neurological symptoms, dyspnea, and/or diarrhea, and significant bleeding. Laboratory tests showed neutrophilia, AM and HP's in every blood smear, coagulopathy, normal cerebrospinal fluid, normal liver transaminases, hypertriglyceridemia, and hypoalbuminemia. Surgical cases were remarkable in that they had small bowel malformations. These cases were subdivided into four distinct groups based on age of presentation, neonates, infants, children and a surgical group. The clinical differences in each group are described.