The aim of this investigation was to study the effect of intra-articular (i.a.) corticosteroid injections (IACIs) in the temporomandibular joint (TMJ) on mandibular development in antigen-induced TMJ arthritis. Ten-week-old female New Zealand white rabbits (n = 42) were randomly divided into four groups: group A, control (no injections); group B, placebo (repeated i.a. TMJ saline injections); group C, untreated arthritis (repeated induction of TMJ arthritis); and group D, steroid (repeated induction of TMJ arthritis + IACI). All animals had two tantalum implants inserted in the right side of the mandible serving as stable landmarks for later growth analysis. One implant was inserted close to the symphysis and one in the molar region. Computerized tomographic (CT) full-head scans were carried out at 14 (T1) and 26 (T2) weeks of age. (Dropout of animals at T2; group C, n = 7, and group D, n = 3.) Absolute and relative intra- and inter-group growth variations were evaluated during the growth period by comparison of CT scans. One-way analysis of variance was used for T1 statistical analysis, and absolute intra-group and relative inter-group growth differences between T1 and T2 were evaluated by Student's t-tests. At T2, the animals in the group A had greater sagittal and vertical mandibular growth compared with the other three groups. TMJ arthritis caused diminished mandibular growth. However, relative mandibular growth was significantly less in group D. The findings of this study do not indicate a positive long-term effect in the use of IACI in the TMJ as an early treatment intervention against TMJ inflammation in growing individuals.