Schizophrenia may be associated with inflammatory reactions and C-reactive protein (CRP) is a nonspecific serum protein marker for persisting inflammatory states. This study aimed to assess concentrations of high sensitivity CRP (hsCRP) in schizophrenic Arab patients and evaluate the relationships of hsCRP levels with aspects of clinical phenotypes of the disease. Two age-matched groups of subjects were studied: (1) healthy controls, HC, n=165; (2) patients with schizophrenia, SZ: n=207. Each subject was evaluated with a standard questionnaire for age at disease onset, family history, disease severity and outcome. Serum hsCRP levels were measured by immunoassay. The two groups of subjects were similar in age, ethnic composition and socioeconomic status. Those with SZ had significantly greater serum concentrations of hsCRP. There were significant associations between hsCRP and (i) age in both groups; (ii) body mass index (BMI) in HC but not in SZ. In the latter, hsCRP levels were: (a) marginally higher in women with later age of disease onset; (ii) highest with remission and with catatonic features; and (iii) lower with family history of psychosis. The study concludes that serum levels of hsCRP are increased in clinically stable Arab patients with schizophrenia and appear related to the disorder's clinical expression. It is suggested that there may be an inflammatory component to schizophrenia which is associated with aspects of its clinical phenotype.