In this study, the methanol extract of Momordica charantia fruit extract was administered to diabetic rats to assess the long term effect of the extract on the lipid proﬁle and the oral glucose tolerance test. Treatment for 30 days showed a signiﬁcant decrease in triglyceride, low density lipoprotein and a signiﬁcant increase in high density lipoprotein level. A signiﬁcant effect on oral glucose tolerance was also noted. Chronic administration showed an improvement in the oral glucose tolerance curve. The effect was more pronounced when the test was done in rats fed the extract on the day of the test compared with tests done in rats which were not fed the extract on the same day. Copyright © 2004 John Wiley & Sons, Ltd.