This study was designed to investigate the effect of formaldehyde-induced arthritis in rat models and evaluate the potency of flaxseed oil (FO) and graviolaleaf extract (GrLE) as anti-arthritic agents. For the study, we used sixty male albino rats which were split up randomly into six equal groups as follows; GroupI: Normal control rats received 0.5 ml/kg b.wt of 9% saline, orally for 2 weeks, GroupII: Injected with FOat a dose of 3.0 ml/kg b.wt by i.p route for 2 weeks, GroupIII: Received GrLE at an oral dose of 100 mg/kg b.wt for 2 weeks, Group IV: Arthritic control group which induced to arthritis by sub planter injection of 0.1 ml of 2% formaldehyde solution v/v through the left hind paw on day 1 and day 3 of the experiment, Group V: Arthritic rats treated with FO, Group VI: Arthritic rats treated with GrLE. The results showed that arthritic untreated rats had signs of macrocytic hypochromic anemia. Also, they showed significant leukocytosis, neutrophilia, lymphocytosis, monocytosis, and eosinophilia. Moreover, they showed a significant thrombocytosis. However, arthritic rats treated with FO and GrLE improved hematological parameters compared to the arthritic untreated group. This suggested that FO and GrLE have anti-arthritic effects against formaldehyde-induced arthritis, likely due to their anti-inflammatory and antioxidant properties.