Individuals born with low birth weight (LBW) risk cardiometabolic complications later in life. However the impact of LBW on general health status and male reproductive function has been scantly analysed. We investigated the clinical and seminal impact of different birth weights (BW) in white-European men presenting for primary couple's infertility. Demographic, clinical, and laboratory data from 827 primary infertile men were compared with those of 373 consecutive fertile men. Patients with BW ≤2500, 2500-4200, and ≥4200gr were classified as having LBW, normal (NBW), and high BW (HBW), respectively. Health-significant comorbidities were scored with the Charlson Comorbidity Index (CCI). Testicular volume was assessed with a Prader orchidometer. Semen analysis values were assessed based on 2010 WHO reference criteria. Descriptive statistics and regression models tested associations between semen parameters, clinical characteristics and BW categories. LBW, NBW and HBW were found in 71 (8.6%), 651 (78.7%) and 105 (12.7%) infertile men, respectively. LBW was more frequent in infertile patients than fertile men (p = 0.002). Infertile patients with LBW had a higher rate of comorbidities (p = 0.003), lower mean testicular volume (p = 0.007), higher FSH (p = 0.02) and lower tT levels (p = 0.04) compared to other BW groups. Higher rates of asthenozoospermia (p = 0.02) and teratozoospermia (p = 0.03) were also found in LBW men. At logistic regression models, LBW was univariably associated with pathologic progressive motility (p≤0.02) and pathologic sperm morphology (p<0.005). At multivariable logistic regression analysis, LBW achieved independent predictor status for both lower sperm motility and pathologic sperm morphology (all p≤0.04). Only LBW independently predicted higher CCI values (p<0.001). In conclusion, we found that LBW was more frequent in infertile than in fertile men. Infertile individuals with LBW showed a higher rate of comorbidities and significantly worse clinical, endocrine and semen parameters compared to other BW groups.