This study aimed to evaluate the effects of omega-3 (ω3) polyunsaturated fatty acids, in association with aspirin (AA), on the morphology of cytokine release in the temporomandibular joint (TMJ) of rats induced with rheumatoid arthritis (IR) by injecting 100 μL of complete Freund’s adjuvant with bovine type II collagen at the tail base. Thirty-two adult male rats were divided into treatment groups: Sham, treated with 0.9% sodium chloride (NaCl) p.o.; IR-control, treated with 0.9% NaCl p.o.; IR-ω3 treated with ω3 PUFAS (85 mg/kg/day p.o.); and IR-ω3 + AA treated with ω3 (85 mg/kg/day p.o.) + AA (20 mg/kg/day i.p.). After maintained treatment for seven days, the animals were euthanized. Bilateral TMJs from each rat were removed and one was subjected to histological immunoassays and enzyme-linked immunosorbent assays to assess interleukin (IL)-1β, tumor necrosis factor-α, and IL-10 levels. Data analysis was performed using the Kruskal–Wallis and Dunn tests. In the IR-ω3 and IR-ω3 + AA groups, the TMJ was greater than in the IR-control group (P < 0.0001). The addition of AA did not improve the effects of ω3 (P = 0.0698). Similarly, the addition of AA conferred no additional effects on the cytokine levels (P > 0.05); however, it increased the proteoglycan density, compared with ω3 alone. We found that ω3 exhibited anti-inflammatory activity in arthritic rats, and the addition of AA increased proteoglycan density, but did not affect cytokine expression.