From 1980 to 1990, 309 cases of haematogenous osteomyelitis were identified in Denmark. Haematogenous osteomyelitis of the vertebral column increased significantly (P < 0.01) from the first to the second half of the period due to an increased number of patients > 50 years of age with community-acquired infection. Vertebral osteomyelitis differed significantly from osteomyelitis of other bones in accordance to age distribution (median 66 vs. 16 years), male/female ratio (75/71 vs. 105/ 58) and patients with diabetes (13% vs. 6%). We found a higher risk of haematogenous osteomyelitis in patients > 50 years of age and among patients with community-acquired infection. The highest incidence (5%) of vertebral osteomyelitis in Staphylococcus aureus bacteraemia in this age group was found in cases without an identified portal of entry. The highest incidence (34%) of osteomyelitis of other bones was found in community-acquired cases in the age group 1-20 years and without an identified portal of entry. The present study discusses reasons for the continued increase of vertebral osteomyelitis among adults and describes incidence rates and major risk factors for developing haematogenous osteomyelitis among patients with S. aureus bacteraemia. We suggest that the localization of haematogenous S. aureus osteomyelitis is connected with the presence of red bone marrow.