Aim: The majority of dental treatments can be performed under local anesthesia. However, sedation or general anesthesia are often required for mentally retarded patients presenting a lack of cooperation. The aim of this study was to retrospectively evaluate the outcomes of mentally retarded patients treated under sedation. Material and Method: The records of the 214 mentally retarded patients that were treated under sedation between 2010-2012 were retrospectively evaluated. The retrospective data included demographic variables, duriation of anesthesia, anti-epileptic drugs used, level of sedation, anesthetic agents, the type of dental treatment and adverse events during and after sedation. Results: In this study the mean age of patients was 22,49 +/- 9,54. The female/male ratio was 109/105. The number of ASA I, II, III patients were 43, 157 and 14 respectively. 16.8% of the patiens (n=36) was on one anti-epileptic drug regimen, while 29.9% of the patiens (n=54) was on more than one anti-epileptic drug regimen. The sedation levels were determined as minimal sedation (6.5%, n=14), moderate sedation (35%, n=75) and deep sedation (58.4%, n=125) respectively. The midazolam-ketamine combination was the most preferred anesthetic regimen (41.1%, n=88). Single dental extraction was the most performed dental treatment (58.4%, n=125). Postoperative nausea and vomiting was encountered in 3.7% of patients (n=8). Respiratuar depression occurred in 2 patients. Two patients developed bronchospasm, while one patient developed postoperative agitation, deep bradycardia and allergic reaction respectively. Discussion: We are of the opinion that sedation can be performed safely by choosing the appropriate drug and method without depressing respiration and reflexes.