Intrauterine insemination (IUI) is a treatment of choice compared with other invasive and expensive techniques of assisted reproduction. Sperm quality is used to predict its outcome and success. Establishing threshold levels for sperm parameters is useful to avoid spending time and money to do other assisted reproductive techniques. This study was carried out to compare various semen parameters in a group of men eligible to participate in an IUI program with those of fertile men whose wives were pregnant at the time of the study. Two hundred and thirty-four semen samples were evaluated from subfertile men whose partners were candidates for IUI and 234 semen samples were evaluated from fertile men whose partners were pregnant less than 12 weeks. To assess the sensitivity and specificity of the main semen parameters, receiver operating characteristic (ROC) curves were used. Normal sperm morphology is more sensitive and specific compared with its progressive motility and concentration. No significant differences in various semen parameters of fertile men and those of the male partners of IUI candidates were observed. ROC analysis identified that sperm normal morphology using strict criteria may be a good indicator of fertility status in men. No significant difference in various semen parameters between the male partners of IUI candidates and the fertile men was seen. However, utilizing ROC curves, sperm morphology using strict criteria could be a good predictor of fertility.