Background Lipid peroxidation of sperm plasma membranes has a deleterious effect on the semen quality, and measurement of malondialdehyde acid (MDA) is the most widely used method for assessing lipid peroxidation. High levels of seminal MDA represent increased lipid peroxidation rates and oxidative damage to the sperm plasma membranes, which may result in the impairment of the integrity and functioning of sperm plasma membranes and damage of both nuclear and mitochondrial DNA. Aim of the study The aim of the present study was to investigate the seminal plasma MDA concentration as a marker of lipid peroxidation and its correlation with the hypo-osmotic swelling test (HOST) scores as a predictor for the functional integrity of the sperm membrane in cases of idiopathic male infertility. Participants and methods A total of 93 men were included in this study: 68 men who had been attending to our andrology outpatient clinics with idiopathic infertility were selected as cases and 25 healthy fertile men were assigned as control group. Both groups were subjected to the following laboratory investigations: semen analysis, peroxidase test, HOST, and measurement of MDA in the seminal plasma. Results Our results showed that seminal plasma concentration of MDA was significantly higher in men with idiopathic infertility compared with the fertile control group ( P ≤ 0.001), and HOST was significantly lower in men with idiopathic infertility compared with the fertile control group ( P ≤ 0.001). In addition, the results showed a strong negative correlation between MDA concentration and HOST ( P ≤ 0.001). Conclusion Our results suggest that the evaluation of lipid peroxidation must be used in combination with the HOST as a diagnostic tool in men with idiopathic infertility in addition to standard semen analysis.