Purpose: To assess the relationship between clinical and semen characteristics and assisted reproductive technology (ART) outcomes with different birth weight (BW) categories in a cohort of infertile men. Materials and Methods: Data from 1,063 infertile men were analyzed. Patients with BW ≤2,500, 2,500–4,000, and ≥4,000 g were considered as having low BW (LBW), normal BW (NBW), and high BW (HBW), respectively. Testicular volume (TV) was assessed with a Prader orchidometer. Serum hormones were measured in all cases. Semen analyses were categorized based on 2021 World Health Organization reference criteria. Sperm DNA fragmentation (SDF) was tested in every patient and considered pathological for SDF >30%. ART outcomes were available for 282 (26.5%) patients. Descriptive statistics and logistic regression analyses detailed the association between semen parameters and clinical characteristics and the defined BW categories. Results: Of all, LBW, NBW, and HBW categories were found in 79 (7.5%), 807 (76.0%), and 177 (16.5%) men, respectively. LBW men had smaller TV, presented higher follicle-stimulating hormone (FSH) but lower total testosterone levels compared to other groups (all p30% (odd ratio [OR] 3.7; p30% (OR 2.9; p