Aim: To determine the most common risk factors of male infertility in Mongolian men attending an infertility clinic. Methods: A prospective, case-control study was conducted in which 430 men were enrolled. All the men had sought their first infertility evaluation between 1998-2002 in the State Research Center on Maternal Child Health, Ulaanbaatar, Mongolia. They were divided into two groups depending on the results of their semen analysis: 191 with abnormal semen and 239 with normal semen profile. Univariate and multivariate analyses were performed to determine any association between risk factors and semen abnormality. Results: Logistic regression analysis demonstrated that the testicular volume, a history of sexually transmitted infections (STI), epididymitis and testicular damage all have statistically significant associations with semen abnormality, when controlled for multiple risk factors. Adjusted odds ratios of 3.4 for mumps orchitis, 2.3 for other orchitis and 3.9 for testicular injury were foun
