Objective: To study the effectiveness and safety of sublingual misoprostol compared with the same dose administered vaginally every four hours for induction of labor at term pregnancy within 24 hours. Materials and Methods: One hundred seventy-six pregnant women of 37 to 42 gestational age fulfilling the study inclusion criteria were recruited and assigned by randomization into two groups. Each group was treated separately by 25-mcg misoprostol sublingually or vaginally every four hours within 24 hours. Results: Mean age of sublingual and vaginal misoprostol group was 25.9±6.9 and 25.5±7.2 years old, respectively, while the mean parity of sublingual and vaginal group was 0.9±1.0 and 1.0±1.0, respectively, which most were first pregnant. Three out of four had no underlying diseases. The initial cervical diameter before receiving misoprostol was 1.7±1.0 and 1.7±0.9 mm, respectively. The total labor time between the two groups was not significantly different. The percentage of success in the sublingual group was more than in the vaginal group, at 79.3 and 74.7, respectively. The side effects of induction were more significantly found in the vaginal group (p<0.05). The pain score was not different, but the satisfactory score was better reported in the sublingual group than in the vaginal one (p<0.05). The Apgar score at 5 minutes of neonates between the two groups were not significantly different (9.8±0.4 and 9.9±0.2). Conclusion: Twenty-five mcg misoprostol administered through sublingual for labor induction in full term pregnant women could not make the total labor time significantly shorter than in the vaginal group. The success rate in the sublingual group was not significantly better than in the vaginal group. The satisfaction was higher in the sublingual group but the pain scores and Apgar score at 5 minutes were not different between the groups.