Objectives: Several side effects can be observed from isotretinoin use, which has been used in acne therapy for years. In this study, the side effects of isotretinoin on skin and mucosa, blood test changes and their relation with total dose were investigated in patients who used equal doses of isotretinoin. Materials and methods: A total of 91 outpatients with acne vulgaris (57 females and 34 males; age range 17-28 years, mean 21 +/- 2.19 years) were enrolled in this study. Skin and mucosal findings and pre- and post-treatment blood tests and their correlation with the total dose were investigated. Student's t-test and the Mann-Whitney U-test were used in the statistical analyses. Results: In all, 89 out of 91 patients completed the study. Cholesterol (p = 0.00), triglyceride (p = 0.00) and low density lipoprotein (LDL) (p = 0.001) levels were found to be significantly elevated. But these values were not over the double of the upper limits. No correlations were found among the total dose and the skin and mucosal changes as well as the blood test results. Conclusion: It is concluded that examination of cholesterol, triglyceride and LDL-cholesterol should be performed monthly if the initial blood tests are close to the upper limits; otherwise, examinations at 2- or 3-month intervals are sufficient, which would save unnecessary costs.