In early diagnosis of sacroiliitis as a part of seronegative spondyloarthritides, conventional radio­graphy and computed tomography are used. Computed tomography was the most sensitive diagnostic method before discovering magnetic resonance imaging. It has been widely accep­ted that computed tomography is the radiological method of choice for detection of early subc­hondral cortical bone erosions. The ideal radiological technique should give the diagnosis before the occurrence of final erosions. The purpose of our study was to establish the role of mag­netic resonance imaging with the resonantic contrast medium Gd-DTPA in early diagnosis of sacroiliitis in patients with suspected ankylosing spondylitis. In 25 patients with clinical diag­nosis of suspected seronegative spondyloarthritis conventional radiography, computed tomo­graphy and magnetic resonance imaging were performed. In 10 patients no abnormalities were demonstrated. In 13 cases computed tomography and magnetic resonance imaging revealed sacroiliitis. In 2 patients with normal plain films and computed tomographs were para- and intraarticular changes of signal intensity in the magnetic resonance images compatible with sacroiliitis. The results of our study suggest that magnetic resonance imaging can be consi­dered as an important modalitiy for early diagnosis of seronegative spondyloarthritides.