The purpose of this study was to determine the diagnostic accuracy of serum inhibin B (INHB) as a predictor of the retrieval outcome of testicular haploid gametes (spermatids and testicular spermatozoa) in nonobstructive azoospermic men.Serum hormone levels,testicular volume,and histological evaluation were performed in 403 Chinese nonobstructive azoospermic men.Testicular haploid gamete was successfully retrieved in 213 of 403 patients (52.85％).The haploid gamete group always had higher INHB levels than the non-haploid gamete group.According to the receiver operating characteristic (ROC) curve analysis,INHB was a good predictor of testicular haploid gamete retrieval outcome in all patients (sensitivity:77.93％ and specificity:91.58％) and patients with normal follicle-stimulating hormone (FSH;sensitivity:88.52％ and specificity:70.83％).The area under the ROC curve (AUC) of INHB was similar to that of FSH in all patients or patients with normal FSH.In patients with elevated FSH,INHB was superior to FSH in predicting the presence of haploid gamete (AUC:0.73 vs 0.55,P＜ 0.05),with a sensitivity of 60.00％ and a specificity of 80.28％.It concluded that serum INHB as an effective marker for spermatogenesis was a significant predictor of testicular haploid gamete retrieval outcomes in nonobstructive azoospermic men.Especially,INHB is superior to FSH in predicting the presence of haploid gamete in the patients with elevated FSH.