The etiology of infertility was evaluated in 98 previously unexamined couples at Helsinki University Central Hospital. Female endocrine disturbances (33%) and male causes (26%) were the most common factors of infertility. Two or more causes were found in 28 couples (29%). Both female and male factors were involved in 8% of cases. Eighteen of 98 women became pregnant during the infertility evaluation before any treatment was given. At four years the cumulative pregnancy rates were 65% for all couples and 60% and 51% for couples with single-factor and multifactorial infertility, respectively. The mean age was significantly higher (p less than 0.05) among those who failed to conceive than among those who conceived. Ovulatory disturbances and multiple causes are common factors in reproductive failure, but even in the presence of multifactorial infertility the primary referrals have good chances of achieving pregnancy.