Identifying predictors of treatment response in patients with the first episode of schizophrenia spectrum disorders is an important issue in the field. The objective of the study was to assess the incidence of poor response to treatment and the factors that influence it in outpatients with the first episode of schizophrenia spectrum disorders. Medical records of the outpatients seeking treatment in 2017 in 3 day inpatient departments of the two districts in St. Petersburg, Russia, were examined. 73 patients diagnosed with schizophrenia spectrum disorders (ICD-10) met the criteria for the first episode (the duration of the disease is up to 5 years, the number of episodes is not more than three) and made up the study group. It has been established that up to 49 % of outpatients with the first episode of schizophrenia spectrum disorders were characterized by poor responses to antipsychotic therapy during outpatient treatment. Factors predicting a poor response to therapy may include earlier onset of illness, concomitant brain damage, and low adherence to therapy.