There is awareness of likelihood of abnormal spermatozoa in obese men; however, results from previous studies are inconclusive. Advances in computer‐aided sperm analysis (CASA) enable precise evaluation of sperm quality and include assessment of several parameters. We studied a retrospective cohort of 1285 men with CASA data from our infertility clinic during 2016. Obesity (BMI ≥30) was associated with lower (mean ± SE) volume (−0.28 ± 0.12, p‐value = .04), sperm count (48.36 ± 16.51, p‐value = .002), concentration (−15.83 ± 5.40, p‐value = .01), progressive motility (−4.45 ± 1.92, p‐value = .001), total motility (−5.50 ± 2.12, p‐value = .002), average curve velocity (μm/s) (−2.09 ± 0.85, p‐value = .001), average path velocity (μm/s) (−1.59 ± 0.75, p‐value = .006), and higher per cent head defects (0.92 ± 0.81, p‐value = .02), thin heads (1.12 ± 0.39, p‐value = .007) and pyriform heads (1.36 ± 0.65, p‐value = .02). Obese men were also more likely to have (odds ratio, 95% CI) oligospermia (1.67, 1.15–2.41, p‐value = .007) and asthenospermia (1.82, 1.20–2.77, p‐value = .005). This is the first report of abnormal sperm parameters in obese men based on CASA. Clinicians may need to factor in paternal obesity prior to assisted reproduction.