AIM: To investigate the expression of cyclin-dependent kinase inhibitors p21 and p27 in gastric well differenti- ated endocrine tumors (GWDET) (ECL-cell carcinoids). METHODS: The expressions of p21 and p27 were ex- amined immunhistochemically in endoscopic biopsy specimens from 16 patients matching the diagnostic criteria of GWDET. Percentage of positive nuclear stain- ing either weak or strong was noted. The association of immunoexpressions with age, gender, tumor localization, multifocality and accompanying chronic atrophic gastritis, neuroendocrine cell hyperplasia (NEH), neuroendocrine dysplasia (NED), intestinal metaplasia (IM), Ki-67 prolif- eration index and clinical outcome were also evaluated. RESULTS: All cases expressed p27 with a mean expres- sion score of 43.6%, while 31.3% of the cases showed any p21 expression. p21 and p27 immunoexpressions were significantly correlated with each other (P < 0.01), and the p21-expressing group had higher p27 expres- sion scores (68% vs 22%). p21 and p27 expressions were lower in women, in non-atrophic mucosa and cases whose tumors were located somewhere other than fun- dus without submucosal extension. On contrary, p21 and p27 expressions were higher in males and the patients with submucosal extension and atrophic gastritis. Cases presenting lower p27 scores had solitary tumors showing neither NEH-NED nor IM. Despite, cases with lower p21 expression presented multifocal tumors accompanied by NEH-NED. However, no correlation of p21 and p27 expres- sions was found with age and Ki-67 expression. CONCLUSION: p27 is widely expressed in GWDETs, while p21 expression is sparse and observed in two thirds of the cases. Loss of p21 and p27 expressions may be cor- related with different carcinoid tumor subtypes; however,m ore studies are needed to assess the role of these pro- spective markers in gastrointestinal endocrine tumors.