The anti-rheumatic efficacy of grape powder (GP) diet was evaluated in transgenic mice (TG) overexpressing human tumor necrosis factor (TNF), a model for rheumatoid arthritis (RA). After 4-weeks, TG mice fed on 10% of GP showed improvement with epiphyseal bone mass (p = 0.07) compared to TG fed on a regular diet. TG mice that received 5 or 10% of GP exhibited a significant (p < 0.05) decrease in resorption-associated osteoclasts in paw and knee joints.