Induction of labor in women with immature cervix was accomplished by four different treatment schedules. The case material included a total of 100 subjects, each treatment group having 25 cases: Group A: Intravenous oxytocin; Group B: Intracervical PGE2-gel followed by intravenous oxytocin; Group C: Intracervical PGE2-gel twice with a 12-hour interval; Group D: Intracervical placebo gel twice with 12-hour interval. Oxytocin did not influence the Bishop score (B.S.) unless in the presence of active labor contractions. In contrast, there was an increment in B.S. by 3.6 points on average within 12 hours following PGE2-gel as calculated from data of subjects without signs of contractions. These results support the concept of a local action of PGE2-gel. The increment in B.S. was larger in subjects with very immature cervices (B.S. less than or equal to 2) than in those with moderately immature scores (B.S. 4). A second PGE2-gel instillation did not increase the B.S. above the level achieved by the first application, indicating that pharmacological ripening of the cervix by a single dose of PGE2 results in an effect approaching maximum. The success rate was the same for oxytocin and PGE2-gel treated women during the first 24 hours, when approximately 40% of the women had given birth. The oxytocin group remained at that level of success rate, whereas the PGE2-gel-oxytocin and PGE2-gel X 2 series continued to improve their success rate up to 75%. An interesting finding in the study was that women given PGE2-gel twice did not need intravenous oxytocin stimulation except in a few cases.