FCA induced arthritis was used to assess the antiarthritic activity of Lactobacillus casei and Lactobacillus acidophilus administered orally as preventive and therapeutic treatments as alone or in combination. Development of paw edema in the right hind limb was measured with a vernier caliper at the end of each week for 21 days. Animals were sacrificed on 22nd day and serum was taken to study various biochemical parameters. Knee joints were also taken for histopathology. Preventive and therapeutic Lactobacillus treatments significantly increased the serum albumin, total protein, alkaline and acid phosphatase and calcium levels of arthritic animals but decreased the (elevated) titers of rheumatoid factor, ceruloplasmin and serum phosphorous levels. Paw inflammation was also decreased by Lactobacillus in both preventive and therapeutic doses. The knee joint histopathologies of arthritic rats treated with Lactobacillus were also normalized. Lactobacillus exhibits protective properties in both preventive and therapeutic approaches.