Purpose: This study systematically searched the dental literature to identify and classify articles on the influence of prosthodontic and dental implant treatment on patient satisfaction and oral health–related quality of life according to their level of evidence. Materials and Methods: A literature search was carried out for articles published between 1960 and February 2003 using an electronic key word search complemented by hand searching. The retrieved articles were subjected to inclusion and exclusion criteria. Only experimental studies were included; articles that did not focus on the effect of therapy on the patient were excluded from further processing. The levels of evidence of the articles were classified following the guidelines of the US Agency for Health Care Policy and Research. Results: A total of 207 publications were identified, of which 114 reports investigating 24,863 patients met the inclusion criteria. Data from the studies were analyzed using SPSS 9.0. Two thirds of the publications showed a low evidence level of III; most were conducted in patients who were edentulous or restored with complete dentures (59% of all studies). Mostly, nonstandardized, custom-made questionnaires (80%) were used. On average, 9 (SD 4.2) outcome variables were used within each trial, but clinical criteria were more often used than psychosocial criteria. The most frequently used questions concerned “chewing function” (86%), esthetics (77%), speech (68%), and general satisfaction (67%). Validated instruments, such as the Oral Health Impact Profile, were increasingly used in recent studies, which were also methodically more sufficient. Conclusion: Few studies with high levels of evidence were found. Research in this field is still in a phase of development. Int J Prosthodont 2004;17:83–93.