Objective: To identify the male molecular causes of failures of IVF (with a deficient binding of spermatozoa to the zona pellucida, without any obvious oocyte anomaly), which are undetected by classical sperm analysis. Design: Case-control prospective study. Setting: University hospital. Patient(s): Proteomic profiles of spermatozoa in patients with a complete failure of fertilization and no spermatozoa bound to the zona pellucida were compared with those of controls (men with normal fertilization and cleavage rates after classical IVF for tubal indication). Intervention(s): All samples were analyzed by two-dimensional fluorescence difference gel electrophoresis (2D-DIGE) after being divided into three fractions according to their isoelectric point. Main Outcome Measure(s): Differentially expressed proteins between infertile men and controls were identified by mass spectrometry. Result(s): Seventeen proteins differentially expressed between cases and controls were found. Twelve of these proteins were identified by mass spectrometry, and two may influence gametes interaction: laminin receptor LR67 and L-xylulose reductase (P34H). Conclusion(s): This study shows that 2D-DIGE might be useful in finding potential targets for diagnosis and prognosis of idiopathic infertility in IVF.