Between 1982 and 1984, at Graz University Obstetric and Gynaecological Clinic, labour was induced in 307 women (146 primiparae and 161 multiparae) by intravaginal administration of 3 mg prostaglandin (PG) E2 tablets, because birth was overdue or because labour was irregular. No risk factors were present when PG was administered: signs of deficiency or postmaturity, or twisted cord, were ruled out. The following complications were evaluated: birth rate and induction-birth interval in relation to cervical maturity and parity. The number of complications was low. It was unrelated to cervical maturity and only partially to parity. Birth was induced successfully with a single dose of 3 mg PG E2 in over 80% of the primiparae and over 90% of the multiparae. The majority of the primiparae and all the remaining multiparae were successfully delivered with a second dose; no relationship between birth rate and cervical maturity was established. Among the primiparae with a low degree of cervical maturity the child was born within 12 hours in over 50% of the cases, among primiparae with more mature cervices in almost 90%. Among the multiparae, the child was born within 12 hours in 90% of the cases regardless of the state of cervical maturity. It is concluded from these results that with appropriate monitoring of birth, intravaginal administration of PG E2 tablets is an efficient and easily managed method of inducing birth at term, involving little risk.