We studied the epidemiology of acute, non-tuberculous, hematogenous vertebral osteomyelitis in Denmark during 1978-1982. 137 patients fulfilled the criteria for acute vertebral osteomyelitis. The incidence was 5/mill/year. There were no cases in the age group 20-29 years. The highest incidence was between 60-69 years (18/mill/year). The prevalence was 15 cases. The mean duration of the disease was 7 months. The lumbar spine was affected in 59%, the thoracic spine in 33% and the cervical spine in 8% of the cases. Insulin-dependent diabetes and treatment with systemic corticosteroids seemed to be significant risk factors, but not rheumatoid arthritis and abuse of alcohol or intravenous drugs. We found no demographic variables of importance for the incidence. In 46%, a primary focus was identified, urinary tract infection being the commonest. According to the National Patient Register 1991-1993, the relative number of reported patients with vertebral osteomyelitis had increased in the age group 20-49 years, compared to 1978-1982, but the incidence was highest in the group aged 60-79 years.