BACKGROUND: Several socio-demographic and clinical factors have been correlated with normal and abnormal seminal fluid indices: male obesity is one of such and has been associated with increases incidence of low sperm concentration and progressively low motile sperm count. This has been linked to endocrine dysregulation resulting from a complexly altered reproductive hormone profile arising from aromatization of fat. OBJECTIVE: To determine the effect of male obesity on semen quality of partners of infertile couples in Ilorin, Nigeria. METHODS: This study was a multi-centred, comparative analytical study that determined the semen parameters and assessed the levels of FSH, LH, estrogen and testosterone amongst obese male partners in infertile couples and compared these results with those male partners in infertile couples with normal BMI (20-25kg/m2 ). There were forty-two obese and normal BMI males respectively obtained by a multi-staged sampling technique.