Objective: To determine the clinical patterns and major causes of infertility in Mongolia, based on the clinical and laboratory findings of both partners, and to compare the findings with data from the published World Health Organization (WHO) multicenter study.

Methods: Four hundred and thirty infertile couples who attended the Infertility Clinic of the State Research Center on Maternal Child Health in 1998–2002 were included in the study. The couples had not had a viable birth after at least 1 year of unprotected intercourse and agreed to be fully investigated according to the WHO protocol ‘Standardized Investigation of the Infertile Couple’.

Results: The mean duration of infertility of couples was 4.9 ± 0.2 years. 43.7% of women had secondary infertility. In the females, the prevalence of past history of sexually transmitted infection (STI) and pelvic inflammatory disease were 33.5% and 25.1%, respectively. In the male partner, 44.2% reported a history of STI and 27.7% had previous testicular damage. 32.8% of women had a tubal factor. The most common causes of male infertility were obstructive azoospermia (8.4%), male accessory gland infection (6.7%) and acquired testicular damage (5.4%). In 45.8% of couples, infertility was due to a female factor and in 25.6% of cases, infertility was due to a male factor. 9.8% of couples had no demonstrable cause in either partner and 18.8% of couples had an infertility diagnosis in both partners.

Conclusion: Patterns of female infertility did not differ significantly from those in the WHO study. Male infertility had a unique pattern, as there was a high prevalence of obstructive azoospermia and previous testicular damage.