The objective of this study was to determine the prevalence, clinical pattern, and management of seronegative spondyloarthropathies (SpA) in the general adult population of Greece. This population-based study was conducted on a target adult (> or =19-year-old) population of 14,233 subjects by rheumatologists who visited households in nine dispersed areas. An interview (standardized questionnaire) was conducted, clinical evaluation and laboratory investigation were done, and established diagnostic classification criteria were used. The age-adjusted and sex-adjusted prevalence (prevalence(asa)) of SpA was 0.49% [95% confidence interval (CI): 0.38-0.60], with a male to female ratio of 5.5:1; the prevalence increased with age until the 59- to 68-year-old age group and declined thereafter. The prevalence(asa) of ankylosing spondylitis (AS) and psoriatic arthritis (PsA) was 0.24% (95% CI: 0.16-0.32) and 0.17% (95% CI: 0.10-0.24), respectively. The mean age (years) at onset was younger in AS (25.83 +/- 6.5) than in PsA (45.24 +/- 12.94) (p < 0.01). Familial clustering was noticed in 5.3% of AS probands. Sacroiliitis was observed in 39.8% and asymmetrical oligoarthritis in 40.6% of PsA patients. Fifty-nine percent of SpA patients had previously visited rheumatologists (91.3% diagnosed correctly vs 11.6% of those who visited other specialists, p < 0.0005); 56.5% of the former had taken disease-modifying antirheumatic drugs compared to none of the latter. The SpA in Greeks are as common as in other European Caucasians, with a high male preponderance. The PsA onset occurs at an older age than AS and frequently presents with a spondylitic pattern. The correct diagnosis was arrived at and appropriate treatment was given when patients consulted rheumatologists.