Due to the heterogeneous distribution of seminiferous tubules (STs) in patients with nonobstructive azoospermia (NOA), retrieving enough good quality spermatozoa for ICSI may require a complete testicular dissection. According to the only available study in this field, spermatozoa may be found in the testis surface in 34.2% of patients, while a deeper testicular dissection is able to provide spermatozoa for ICSI in 28% of those without spermatozoa in the testis surface. To determine the probability of finding enough spermatozoa for ICSI at the initial wide incision of the testis in a cohort of men with NOA undergoing microdissection testicular spermatozoa extraction (mTESE). We evaluated 276 patients, aged 37 (20-62) years, who underwent unilateral (86, 31.15%) or bilateral (190, 68.8%) mTESE from January 2018 through December 2021. During mTESE, the entire surface of the testicular parenchyma was explored first in search for dilated STs: if no/ not enough spermatozoa were retrieved, the deeper portion of the parenchyma was explored. Spermatozoa were retrieved in 137 patients (49.6%). Histopathology demonstrated Sertoli-cell only syndrome in 65.6% of operated testes, while maturation arrest was found in 19.5%, hypospermatogenesis (HS) in 12.7%, and hyalinosis in 2%. Spermatozoa were obtained from the testis surface in 46 of 276 patients (16.6%), and after a complete dissection in 91 subjects (32.9%). On multivariate logistic regression, only the histopathological subcategory HS was predictive of the chance of retrieving spermatozoa from the surface of the testis (OR 3.24, 95% CI 1.37-7.69, p=0.007). Most patients with NOA, particularly those with unfavorable histopathological patterns, require a complete dissection of the testicular parenchyma to obtain enough good quality for ICSI. By enabling the complete exploration of the testicular parenchyma, mTESE is to be preferred to cTESE to retrieve spermatozoa in patients with NOA.