Positive and negative symptoms are measurable characteristics that may represent core features of schizophrenia and offer a quantitative approach for studying the genetics of schizophrenia and related disorders. The Positive and Negative Syndrome Scale (PANSS) was used to assess 72 members of five families segregating schizophrenia. The study confirmed high internal reliability of PANSS scales in this sample with diverse lifetime diagnoses. Gender but not alcoholism affected scores. Schizophrenia/schizoaffective and schizophrenia spectrum disorder groups had higher mean scores for the positive and negative scales than other lifetime diagnostic groups, consistent with genetic transmission of these symptoms. Positive and negative symptom patterns did not subtype families. The results support the validity of positive and negative symptom measures as independent dimensions in familial schizophrenia.