Introduction: Body mass index BMI is a risk factor that influences semen quality and reduces male fertility. The aim of this study was to determine the impact of body mass index (BMI) on semen parameters in infertile men.
 Subject and method: A total of 446 infertile men, the study population was divided into four groups depending on their BMI , underweight (<18.5 kg/), normal weight (18.5-24.99 kg/m2 ), overweight 25-29.99 kg/m2), and obese >30.0 kg/.semen parameters (PH, volume, concentration ,total semen count ,vitality, morphology and motility ) were compared across the four BMI groups.
 Results: The mean of age was 41.91±6.39, the mean infertility duration was 4.92±3.28, 351(78.7٪) had primary infertility and 95(21.3٪) had secondary infertility. The mean BMI was 29.38± 4.85 and the most of patients 45.2٪ were obese.
 Conclusion: This study has found evidence of an association between BMI and semen parameters (Sperm concentration, Total sperm count, motility, and vitality) and no correlation between Semen volume, morphology and BMI.
 Keywords: Body mass index, male infertility, semen quality, west of Algeria