Objective Oral contraceptive pills (OCPs) are one of the most effective reversible and accessible contraceptives, and patient acceptance for their use depends partly on the unfavorable adverse effects. The present study compared the two kinds of OCPs (monophasic; levonorgestrel (LNG)–ethinyl estradiol (EE) 150/30 versus triphasic; LNG–EE 50–75–125/30–40–30) for adverse effects and patient satisfaction. Study design A randomized clinical trial was performed on 314 women who used OCPs for the first time, as their contraception, for 6 months. Overall, 1884 cycles were studied. In the monophasic group ( n = 159 who finally finished the study), monophasic pills LNG–EE 150/30 mcg, and in the triphasic group ( n = 155 who finally finished the study), triphasic pills LNG–EE 50–75–125/30–40–30 mcg were used. Statistical analysis was performed using SPSS 10: Chi square test, Fisher exact test and Student's t-test were used. Results There were no significant differences between the two groups for common side effects, including nausea, headache, nervousness, facial hyperpigmentation (chloasma), and body weight (increase or decrease) but breakthrough bleeding and spotting (BTB/S) were less in the triphasic group, occurring in 30 cycles (18.86%) versus 10 cycles (6.45%), P = 0.009*. Patient satisfaction for the two OCPs was similar and high. The rates of side effects were low. Conclusion It seems that the monophasic and triphasic pills are similar according to patient satisfaction and side effects; therefore there is no benefit of one over the other except for BTB/S, for which triphasic is superior.