Objective To study the influence of a multi‐component nutrient dietary supplement on sperm parameters and pregnancy rates in idiopathic male infertility (IMI) with oligo‐, astheno‐, and teratozoospermia. Design A randomized, double‐blind, placebo‐controlled, prospective, parallel arms (1:1 allocation ratio), multi‐center clinical trial. Settings Eight urology/reproductive health clinical centers located in Ukraine. Patients Eighty‐three males aged 21‐50 years with IMI and at least 1 of 3 abnormal values: total sperm concentration < 15 million/ml or/and spermatozoa progressive motility < 32% or/and forms with normal morphology < 4%. Intervention(s) Patients were randomly allocated verum test dietary supplement (TDS) containing l‐carnitine/acetyl‐l‐carnitine, l‐arginine, glutathione, co‐enzyme Q10, zinc, vitamin B9, vitamin B12, selenium, or placebo 1 time daily for 6 months. Main Outcome(s) The primary outcome measure was the percentage of normal spermiograms (concentration ≥ 15 million/ml and ≥ 32% of spermatozoa with progressive motility and ≥ 4% of normal forms) at month 0, 2, and 4. The percentage of pregnancies served the secondary outcome endpoint. Differences between the groups were assessed in z‐test for proportions. Results All males finished the study. At month 4, 29/42 (69.0%) males in the verum and 9/41 (22.0%) had normal spermiograms (P < .001). The percentage of spontaneous pregnancies in the verum group was greater than in the placebo group (10/42, 23.8% vs. 2/41, 4.9%, respectively, P = .017). There were no reportable supplement‐associated adverse events. Conclusion Specific multi‐nutrient combination l‐carnitine/l‐acetyl‐carnitine, l‐arginine, glutathione, co‐enzyme‐Q, zinc, folic acid, cyanocobalamin, and selenium can improve sperm quality in males with IMI and increase pregnancy rates.