Intra-articular injections of triamcinolone hexacetonide (THA) are a useful therapy in JRA and HLA B 27 related arthritis (B 27 RA). Published data have indicated good results and few side effects. We evaluate here the frequency of occurrence of local side effects in 35 children with JRA (115 joints treated) and 13 children with B 27 RA (29 joints treated). With a mean follow up of 25 months in JRA and 18 months in B 27 RA, we observed 12 cases (8.3%) of subcutaneous tissue atrophy with local depigmentation (knees 5 cases, wrists 2 cases, ankles 3 cases, metatarsophalangeal joints 2 cases) and 7 cases (4.9%) of intra-articular calcifications all in the JRA group (wrists 3 cases, knees 2 cases, ankles 2 cases). Youth and joint size are possible predisposing factors for subcutaneous tissue atrophy and intra-articular calcification. Spontaneous improvement previously reported for these local side effects was not observed in our study. These results underline the necessity of discussing on a case by case basis whether intra-articular, non long-acting corticosteroid or THA are indicated. THA must be injected with a rigorous technique and with a dosage adapted to the articular volume.