Background: Previous research on the aetiology of infertility in sub-Saharan Africa was generally clinic based and it is not known whether findings from this work are representative of the general population. A better understanding of the medical causes of infertility is crucial for reducing the incidence of infertility and for improving the clinical management.

Objective: To determine the type and aetiology of infertility in a community and clinicbased sample.

Design: Couples identified as infertile in a representative cross-sectional survey from a community-based sample of 2019 women aged 20-44 years and couples seeking care for infertility at a tertiary health facility.

Setting: The community-based sample was drawn from Moshi Urban District and the clinic-based sample from patients seeking care at Kilimanjaro Christian Medical Centre (KCMC) in 2002 and 2003.

Participants: Sixty six couples identified as infertile in the community-based sample and 112 couples seeking care for infertility.

Results: The percentage of primary infertility was 37.1% and secondary infertility was 62.9%. Female only factor infertility was identified in 65.9% of the couples, male only factor in 6.8%, male and female factors in 15.2% and unexplained infertility in 12.1%.

Conclusion: The type and aetiology of infertility were the same in the community and clinic-based sample suggesting that the couples seeking infertility health care were representative of the general infertile population. Tubal factor infertility was the commonest cause.