In an earlier study we showed that tretinoin could prevent corticosteroid-induced skin atrophy in hairless mice. In this study, we examined the histochemical, biochemical, and immunochemical changes that accompanied the atrophy and its prevention. Mice were treated dorsally for 3 weeks in the morning and afternoon (AM:PM) as follows: 1) vehicle:vehicle, 2) steroid:vehicle, 3) steroid:tretinoin. Tretinoin concentration was 0.05% in an ethanol:propylene glycol vehicle. The steroid was clobetasol propionate (0.05%). The normally sparse dermal glycosaminoglycans were further reduced by steroid:vehicle treatment and increased to greater than vehicle:vehicle amounts by steroid:retinoid. Mast cells were similarly affected. Biochemical quantification of glycosaminoglycans confirmed the histochemical findings. Collagen, non-collagenous protein, and total protein content were reduced by the steroid. The latter two were returned to more normal levels by tretinoin whereas with collagen there was only a trend toward normal levels. Fibronectin, which was increased by the steroid:vehicle treatment, was reduced to more normal levels by steroid:tretinoin. We conclude that tretinoin has the ability to prevent the major steroid-induced biomechanical changes in hairless mouse dermal connective tissue that contribute to atrophy.