It was clinically evaluated by double blind method whether co-enzyme Q10 has protective effects on hair loss caused by anthracycline antibiotics. Six cases of acute leukemia, 2 blastic crisis of CML and 11 malignant lymphoma were entered to this study. DCMP regimen for acute leukemia for VEPA for lymphoma were performed. Coenzyme Q10 (or placebo) of 120 mg/day was orally administered. The grade of hair loss was classified into five groups. Five cases were only given to DM and 3 cases receiving DM and CoQ10. ADM was 6 cases and 5 were combined with CoQ10. No significant diffehence in effect of CoQ10 administration rence was recognized between two groups statistically. Elevations of GOT and GPT were less frequent in the group receiving CoQ10.