We describe the genetic and demographic characteristics of patients with amyotrophic lateral sclerosis (ALS) in Flanders, Belgium. Prognostic factors related to survival are examined. ALS was familial in 8.6% of all MND patients. In 6 of 8 apparently unrelated families, an SOD1 mutation was found. In sporadic ALS, mean age at onset was 57.1 years. There was a male preponderance (1.2:1) and the disease had a bulbar onset in 19%. Median survival was 32 months (95% CI 26-46). The presence of an APOE-epsilon 4 allele was not associated with a bulbar onset of ALS, an earlier age at onset or a shorter median survival. Variables examined in a multivariate analysis included age, sex, site of onset, delay from onset to diagnosis, and % forced vital capacity. Shorter survival was independently associated with higher age, bulbar onset, a short diagnostic delay, and a lower percent-predicted vital capacity at study entry. Simple clinical baseline characteristics can assist the clinician in estimating prognosis in ALS. The demographic characteristics of the Flemish ALS population do not seem to differ from those described in other parts of the world.