14-3-3 sigma is an exclusive epithelial marker and data on its expression in different malignancies are very scarce. The aims of the present study are to screen its expression in the most common neoplasms occurring in the urological and gynecological tract and to evaluate its use as a diagnostic marker. A tissue microarray was constructed using 350 samples from 13 different neoplasms. Immunohistochemical analysis using a polyclonal 14-3-3 sigma antibody was performed. Overall, this protein was positive in 141 and negative in 209 tumors. The most frequent expression was seen in squamous cell carcinoma of the cervix and urothelial bladder carcinoma, followed by prostatic and endometrial adenocarcinoma. 14-3-3 sigma was able to distinguish prostate adenocarcinoma from urothelial bladder carcinoma, with an odds ratio of 0.028 (P = 0.001; 95% CI, 0.0003-0.222), and distinguish seminoma from embryonal carcinoma of the testis, with an odds ratio of 0.061 (P = 0.009; 95% CI, 0.007-0.5014). It also has a good value in differentiating renal clear cell carcinoma from papillary carcinoma, with an odds ratio 0.470 (P < 0.001; 95% CI, 0.008-0.261). 14-3-3 sigma seems to have good potential use as an epithelial marker, after confirmation with further targeted studies. Finally, as with all immunohistochemical markers, we can optimize the utility of this protein to distinguish tumor mimics by including it in an appropriate immunohistochemical panel.