Intra- or periarticular osteoid osteoma (00) is uncommon, and therefore a diagnostic challenge. Symptoms are: chronic synovitis, decreased range of motion, joint effusion, and joint contracture. Radiographically, the classical perifocal sclerotic margin is often absent, which leads to a significant delay in diagnosis. The authors retrospectively studied 50 cases of intra- and peri-articular OO, treated with percutaneous destruction and alcoholisation. The mean follow-up period was 8.7 years (range, 1 to 15 years). The diagnosis was only made after +/-14 months (range, 8 to 18 months), due to atypical symptoms (nightly pain absent in 38%) and uselessness of plain radiographs (in 100%). CT-scan, contrast enhanced MRI and bone scan brought the solution. The technique was successful in 48 out of 50 cases (96%): incomplete excision occurred in 2 patients. The diagnosis of intra- or periarticular OO should be considered in case of unexplained joint pain where conservative treatment is inefficient.