The objective of the current study was to investigate the treatment outcomes for the use of cyclophosphamide, adriamycin, vincristine, and prednisolone (CHOP) chemotherapy in adult patients with hemophagocytic lymphohistiocytosis (HLH). Seventeen HLH patients older than 18 yr of age were treated with CHOP chemotherapy. A response evaluation was conducted for every two cycles of chemotherapy. With CHOP chemotherapy, complete response was achieved for 7/17 patients (41.2%), a partial response for 3/17 patients (17.6%), and the overall response rate was 58.8%. The median response duration (RD) was not reached and the 2-yr RD rate was 68.6%, with a median follow-up of 100 weeks. Median overall survival (OS) was 18 weeks (95% CI, 6-30 weeks) and the 2-yr OS rate was 43.9%. Reported grade 3 or 4 non-hematological toxicities were increased serum liver enzyme levels and stomatitis. Grade 3 or 4 hematological toxicities were leukopenia (50.8%), anemia (20%), and thrombocytopenia (33.9%). Neutropenic fever was observed in 21.6% of patients (14/65 cycles), and most of the cases were resolved with supportive care including treatment with broad-spectrum antibiotics. CHOP chemotherapy seems to be effective in adult HLH patients and the toxicities are manageable.