ABSTRACT: Multiple semen analyses are important for identifying patients with severe oligozoospermia (SOS) or cryptozoospermia (CZO). Moreover, clinical predictive factors for CZO and SOS are warranted. Therefore, we aimed to identify predictors of sperm retrieval in patients with a prior diagnosis of nonobstructive azoospermia (NOA) based on repeat semen analysis. We retrospectively included 209 patients diagnosed with NOA. Data regarding age at diagnosis, body mass index, testicular volume, serum luteinizing hormone, follicle-stimulating hormone (FSH) and testosterone levels, smoking history and testicular microlithiasis were analyzed. Patients were classified into the falsely reported azoospermia (FAZO) and true azoospermia (TAZO) groups. Furthermore, FAZO-related factors were evaluated using the Mann-Whitney U test and univariate and multivariate analysis logistic regression models. Regarding FAZO-related factors, the cut-off level was determined using receiver operating characteristic (ROC) curve analysis. Among 209 patients with NOA, 33 (15.8%) had spermatozoa identified in subsequent semen analyses. Multivariate analysis revealed that the FAZO group had significantly lower FSH levels than the TAZO group. ROC curve analysis showed that the cut-off value for the FSH level was 15.3 mIU/mL, with 26 (78.8%) and 29 (16.5%) patients in the FAZO and TAZO groups, respectively, having FSH levels ≤15.3 mIU/mL. In conclusion, the FSH level was a predictive factor for FAZO. In patients diagnosed with azoospermia who have relatively low FSH levels, multiple semen analyses might facilitate identification of sperm in ejaculated semen. LAY SUMMARY: We evaluated 209 patients diagnosed with spermless semen at prior medical institutions. After thorough semen analyses at our hospital, sperm were identified in the ejaculates of 33 (15.8%) patients. We performed comparisons between patients with and without identified sperm. The serum FSH level was identified as a significant predictive factor for sperm presence. FSH stimulates testicular growth and function and promotes sperm development. Patients who had relatively low and high FSH levels for patients with spermless semen had an increased and decreased chance, respectively, of having sperm identified in ejaculated semen through repeat thorough semen analyses. Sperm might be identified in ejaculates of patients diagnosed with spermless semen who have relatively low FSH levels.