The article presents a case of induced delusional disorder in a 23-year-old female patient with coexistent schizotypal disorder. In the patient, bizarre beliefs, strange interests as well as blunted affect and social withdrawal have been observed since adolescence. After becoming involved with a religious group, the patient developed intense delusions. Analysis of the patient’s life situation and the course of illness allowed induced delusional disorder to be diagnosed. After admission to an inpatient clinic, antipsychotic treatment was introduced, and the patient was isolated from the group. It resulted in a significant improvement of psychiatric status. After more than a year following hospitalization, the patient presented criticism of previous psychotic disturbances and declared a definite improvement in mood and overall functioning. These observations were confirmed by the family of the patient. The patient finished her studies, defended her master’s thesis and planned to pursue her further professional career plans.