Transforming growth factor beta s (TGF beta s) are potent immunosuppressive molecules released in the brain after injury. We hypothesized that TGF beta levels in cerebrospinal fluid (CSF) of schizophrenic patients would be altered because TGF beta can influence neural cell adhesion molecule (N-CAM) expression in vitro. The levels of TGF beta 1 and beta 2 in CSF of patients with schizophrenia and normal controls measured by ELISA showed no differences. There was evidence that the stability of TGF beta in CSF may be altered in schizophrenia. For a limited sample, TGF beta 1 and N-CAM concentrations were significantly correlated in normal patients (r = 0.98) but not in schizophrenics. The results do not support an active neurodegeneration or anti-inflammatory response in the central nervous system, which is reflected in the CSF of chronic schizophrenics.