The asymptomatic people are highly responsible for the spread of the cryptosporidiosis in the community. In addition, the infection might become symptomatic when the immune system of the asymptomatic individuals converts to weakness. In the our study, Cryptosporidium parvum oocysts were investigated in duodenal biopsy and stool specimens of 100 individuals undergoing endoscopy but not having any symptoms for cryptosporidiosis who applied to the outpatient services of Departments of Gastroenterology of Gulhane Military Medical Academy and Gazi University Medical Hospital. The study group is comprised of 47 females and 53 males between the ages of 19-71 (the mean of age 40.1 years). In the present study, of these stool specimens, three (3%) were positive for C. parvum, but not negative in their duodenal biopsy specimens. The staining methods used modified acid-fast, Kinyoun acid-fast, trichrome, carbol fuchsin and safranin for the stool specimens; Kinyoun acid-fast, trichrome, safranin and haematoxylin eosin for the duodenal biopsy specimens. As C. parvum oocysts were easily detected in the stool specimens of three individuals used by staining of modified acid-fast, Kinyoun acid-fast, trichrome, and carbol fuchsin, but were negative by staining of safranin. So, it seemed to be likely that Kinyoun acid-fast and carbol fuchsin staining techniques were the most powerful ones among the various staining methodes for the diagnosis of cryptosporidiosis and would be preferred for their simplicity in application and research. We concluded that C. parvum oocysts should also be routinely examined in the stool specimens in the Microbiology Laboratory due to the fact that the prevalence of C. parvum in asymptomatic individuals was found to be 3% in the present study.