Previous investigations have shown that the transforming growth factor-beta 1 (TGF-beta 1) may protect neurons against excitotoxic and oxidative damage and may inhibit apoptosis. The aim of this study was to investigate the role of TGF-beta 1 in patients with amyotrophic lateral sclerosis (ALS). The study involved 24 ALS patients and 15 control group people. The ALS patients were divided into groups according to their clinical status, and duration of ALS. The TGF-beta 1 in the serum and cerebrospinal fluid (CSF) was measured by the enzyme-linked immunosorbent assay (ELISA). Results showed that TGF-beta 1 concentrations in the serum, and CSF in the whole group of ALS patients did not differ from those of the controls, but the serum TGF-beta 1 concentration was significantly higher in ALS patients with a terminal clinical status than in controls. The TGF-beta 1 concentration was significantly higher in the CSF of the patients, with a long duration of ALS, than in the patients with a short duration of ALS, and there was a significant positive correlation between the CSF TGF-beta 1 and the duration of ALS. TGF-beta 1 may play a role in neurodegeneration of ALS, and may be an indicator of the duration of the disease.