The records of 227 couples who received artificial insemination by frozen donor semen in 984 treatment cycles were analysed to find out the factors affecting the pregnancy rates. The cumulative pregnancy rate at 6 months was 46.8% and the pregnancy rate per cycle was 10%. The pregnancy rates were adversely affected by (1) increase in the recipient age above 30 years, (2) irregularity of menstrual cycles, (3) the use of clomiphene citrate for induction of ovulation, and (4) low cervical mucus scores. Among our donor semen samples selected with a set of criteria, the sperm counts and initial and post-thaw motility did not affect the pregnancy rates.