Objective: The evaluation of serum osteocalcin (OSN) for Iraqi infertile patients to see the effect of osteocalcin insufficiency, which may lead to a decreased level of testosterone production in males that may cause infertility. Methods: Forty two newly diagnosed infertile males age range (24–47) years and thirty two apparently healthy males as controls age range (25–58) years. Serum levels of testosterone (TEST), stimulating follicle hormone (FSH) and luteinizing hormone (LH), prolactin (PROL), osteocalcin OSN, and fasting blood sugar (FBS) were performed in both patients and controls. Estimation of serum OSN by Immulite1000 auto-analyzer, TEST, FSH, LH, PROL, and FBS by Immulite2000 auto-analyzer. Results: Infertile patients show significantly elevated serum levels for follicle-stimulating hormone (FSH), LH, and PROL as compared with controls according to p-value ( 0.000), (0.044), and (0.000), respectively. On the other hand, the infertile patients have lowered serum levels for OSN and TEST as compared with controls according to p-value (0.000) and (0.000), respectively. Fasting blood sugar (FBS) is evaluated within the normal levels for both patients and control groups. Conclusion: Osteocalcin, act as a regulator of male fertility via its role in the biosynthesis of testosterone, so it serves as a biomarker for evaluation of male infertility. Therefore, osteocalcin could be used as a therapeutic for the treatment of disorders related to male reproduction, including male infertility and low testosterone levels.