Homogenates of postmortem spinal cord from seven patients with amyotrophic lateral sclerosis (ALS) and six controls together with serum from 13 patients with ALS and 13 controls were analysed for vascular endothelial growth factor (VEGF) using an immunoassay (ELISA). There was no significant difference in VEGF levels in the spinal cord between the ALS patients and the controls. In serum the VEGF levels were significantly higher in the ALS group than in the control group. There was a moderate inverse relation between the duration of the disorder and the serum VEGF levels. The findings indicate that the capacity to synthesize VEGF is preserved even in the late stages of ALS. The results might also be consistent with a transient hypoxic component during the course of ALS, but not with a persistant spinal hypoxia in the late stages of the disorder.