After pantethine in doses of 540 mg per day was administered for 8 weeks in 20 patients with hyperlipidemia, the serum levels of total cholesterol, triglyceride and HDL-cholesterol were compared with the pretreatment level. The serum level of total cholesterol decreased to 240±52 mg%[mean±standard deviation] after 4 weeks and 223±41 mg% after 8 weeks from the pretreatment level of 293±38 mg%(p<0.01). The serum triglyceride level also decreased to 254±109 mg% after 4 weeks and 239±114 mg% after 8 weeks from the pretreatment level of 375±126 mg%(p<0.01). But, there was no significant change in the serum levels of HDL-cholesterol before and after treatment (56±27 mg% beforAfter pantethine in doses of 540 mg per day was administered for 8 weeks in 20 patients with hyperlipidemia, the serum levels of total cholesterol, triglyceride and HDL-cholesterol were compared with the pretreatment level. The serum level of total cholesterol decreased to 240±52 mg%[mean±standard deviation] after 4 weeks and 223±41 mg% after 8 weeks from the pretreatment level of 293±38 mg%(p<0.01). The serum triglyceride level also decreased to 254±109 mg% after 4 weeks and 239±114 mg% after 8 weeks from the pretreatment level of 375±126 mg%(p<0.01). But, there was no significant change in the serum levels of HDL-cholesterol before and after treatment (56±27 mg% before treatment, 56±18 mg% after 4 weeks and 59±22 mg% after 8 weeks). Pantethine was well tolerated in most patients.