Aim. To study a trend in active sacroiliitis (ASI) in patients with axial spondyloarthritis (axSpA) during different short-term regimens using etoricoxib (ET) 90 mg. Subjects and methods. Forty patients with axSpA, including 30 with ankylosing spondyloarthritis), and ASI (sacroiliac joint (SIJ) osteitis as evidenced by magnetic resonance imaging) were examined and then randomized to 2 groups: 1) 20 patients who took ET 90 mg four days or more a week; 2) 20 patients who received ET 90 mg 3 days or less a week. Osteitis was measured in 4 quadrants of each SIJ (0-3 scores). Its main criterion was considered to be a decrease in total osteitis activity (TOA) 12 week later. Results. In all the patients (n=40), TOA decreased from 6.5 (4; 9) to 2 (0; 5) scores (p<0.0001). In Group 1 (n=20), that reduced from 6.5 (4; 8.5) to 0 (0; 3) scores (p<0.0001). In Group 2 (n=20), that did from 6.5 (4; 10) to 4 (1; 8) scores (p=0.49). At 12 weeks, in in Groups 1 and 2, the difference in final TOA achieved no statistical significance (p=0.056). In these groups, there were 19 (95%) and 14 (70%) treatment-responsive patients, respectively. Conclusion. The intake of ET 90 mg for 12-weeks is associated with a reduction in the degree of ASI in patients with axSpA. The use of ET 4 times or more a week is more effective in diminishing osteitis than that of ET 3 days or less.