Aim: Although one-fourth of the pituitary tumors are inactive and silent, increased total volume of the pituitary gland exerts pressure on sella turcica and corrodes the clinoid processes, resulting in several problems. Therefore, determination of the prevalence of the concealed pituitary tumors is of major concern among clinical practitioners. This study was performed to determine the prevalence of these tumors in cadavers referred to the Iranian Legal Medicine Organization (Kahrizak, Tehran). Materials and Methods: This cross-sectional descriptive study was performed between June 2007 and February 2008. A total of 485 cadavers were selected by simple random sampling method. Pituitary glands were removed and then horizontally cut and four slides were prepared from each of them, stained by hematoxylin and eosin, and evaluated by a light microscope. For statistical analysis, SPSS software (version 16), Mann-Whitney U test, Kolmogorov-Smirnov nonparametric test (K-S test), and Chi-square test were used. Results: Of the 485 investigated cadavers, 365 (75.3%) were males with an average age of 42 ± 20.5 years and 120 (24.7%) were females with an average age of 44 ± 22 years. A total of 61 (12.6%) had concealed pituitary masses. No statistically significant difference was found between the mean age, sex, and body mass index (BMI) of the cadavers with and without concealed tumors (P=0.380 P=0.450, and P=0.884, respectively). Conclusions: In the present study, the prevalence of the concealed pituitary adenomas was 12.6%. There was no correlation between age, sex, and BMI and the prevalence of the concealed masses.