A population survey of the Sami (Lapp) population of the municipalities Karasjok and Kautokeino in north Norway revealed a prevalence of ankylosing spondylitis (AS) according to the New York criteria of 1.8%. Eleven cases of AS were found, 7 men and 4 women. Only 4 of the 11 observed cases of AS were aware of the diagnosis of AS prior to the survey. Ten of 11 patients with AS possessed HLA-B27 (91%) which is found in 24% of the general Sami population in this area. It was calculated that 6.8% of B27 positive persons had AS.