The Helsinki High-Risk (HR) Study is a follow-up study of 179 offspring born to mothers with DSM-IV-TR diagnoses of schizophrenia, schizoaffective disorder, other schizophrenia spectrum disorders, and affective psychoses. Mothers comprised all female patients born between 1916 and 1948 who had been treated with hospital diagnoses of schizophrenia, schizophreniform, or schizoaffective psychoses in any mental hospital in the city of Helsinki up to 1974, and who had given birth in Helsinki between 1960 and 1964. In this report we conducted a principal factor analysis of maternal symptoms using 12 items of the Major Symptoms of Schizophrenia Scale (MSSS), the global ratings of anhedonia-asociality and avolition-apathy from the Scale for the Assessment of Negative Symptoms (SANS), and the global rating of bizarre behavior from the Scale for the Assessment of Positive symptoms (SAPS), and examined whether the factor scores predicted the offspring's morbidity from psychotic disorders. We found a four-factor solution (negative, positive, catatonic, and affective symptom factors). High maternal positive symptom factor score significantly predicted decreased morbidity from schizophrenia among offspring (P=0.0098). Our result suggests that maternal positive symptoms are less harmful to the child than other maternal psychotic symptoms, and supports the view that positive symptoms are non-specific symptoms of psychosis rather than core features of schizophrenia.