Purpose: The objective of this study was to use an oral stereognosis test to evaluate possible intraoral/sensorimotor causes in patients with a psychologic diagnosis of psychogenic prosthesis incompatibility, and to evaluate possible correlations between oral stereognosis and the psychologic diagnostic tools Symptom Checklist-90-R (SCL-90-R) and Center of Epidemiological Studies Depression Scale (CES-D). Materials and Methods: The study cohort comprised 83 patients with complete dentures fabricated according to a standardized protocol. Twelve patients diagnosed with psychogenic prosthesis incompatibility (11 women, 1 man) using the SCL-90-R and CES-D scales in a previous study and a group of 24 randomly selected control subjects (14 women, 10 men) underwent an oral stereognosis test with 10 neutral-tasting plastic test specimens with a maximum edge length of 8 mm in 2 test cycles. Results: The results revealed no significant differences in oral stereognostic ability between patients with diagnosed psychogenic dental prosthesis incompatibility and the control patients. The patients in the test group expressed clear dissatisfaction with their dentures. No correlation was found between oral stereognostic ability and the SCL-90-R or CES-D values. Conclusions: This study is the first to use oral stereognosis tests for patients with psychologically diagnosed psychogenic dental prosthesis incompatibility. The diagnosis of psychogenic prosthesis incompatibility by the SCL-90-R and CES-D scales is affirmed by the lack of correlations between the functional/anatomic aspects of oral stereognostic ability, psychologic diagnostic tools, and the clinical picture of psychogenic prosthesis incompatibility. Thus, psychogenic prosthesis incompatibility can be classified more explicitly as a psychosomatic disorder.