SUMMARY Radiological abnormalities are often seen at the pubic symphysis in rheumatic disorders. In a radiological study of 120 patients with rheumatic diseases osteitis pubis with erosive and sclerotic changes was a feature of ankylosing spondylitis. Irregularity and subluxation were not related to osteitis pubis or diagnostic group but were common in females and had a possible association with previous pregnancy.The radiological changes at the pubic symphysis of osteitis pubis have been recognised for more than 50 years. Early reports related osteitis pubis to urological disease, prostatectomy, and pelvic surgery. Subsequently other causes have been described, including pregnancy and trauma (Wiltse and Frantz, 1956;Coventry and Mitchell, 1961;Harris and Murray, 1974).A number of rheumatic disorders have been associated with radiological abnormalities of the pubic symphysis. The commonest of these are ankylosing spondylitis, rheumatoid arthritis, and to a less extent osteoarthritis (Coventry and Mitchell, 1961;Dilsen, et al. 1962). But there is little detailed information on the nature, frequency, extent, and interrelationships of abnormalities at the pubic symphysis in these diseases.In the present study radiological changes at the pubic symphysis have been examined in patients with ankylosing spondylitis, rheumatoid arthritis, and osteoarthritis. Pain of insidious or sudden onset is the predominant symptom associated with osteitis pubis, and the significance of this has been considered in relation to the radiological changes.As pregnancy and trauma are 2 causes of osteitis pubis which could also be involved in at least some patients, the possible significance of these factors has also been considered.Radiological fluffy periostitis of the inferior pubic ramus is an additional feature considered to be associated with ankylosing spondylitis (Dilsen et al., 1962). Radiographs have been analysed in the present study for such changes and their relationship to changes at the symphysis pubis considered.