The efficacy of Rituximab (RTX) has been examined in Ankylosing Spondylitis (AS) and Rheumatoid Arthritis (RA) before. Here, we have reported the case of a patient with RA and AS showing good clinical improvement with RTX. A 47-year-old female patient being followed by RA diagnosis presented with bilateral wrist pain and swelling for three months. Previously, she had received multiple DMARDs with poor response. For her ongoing active disease, Disease Activity Score 28 (DAS28=7.3) RTX 1000 mg was administered at 0 and second weeks. She had chronic inflammatory lower back pain with morning stiffness, which improved on exercise and hot shower since last two years. Suprapubic pelvis Anterior Posterior (AP) radiography and sacroiliac Magnetic Resonance Imaging (MRI) showed bilateral sacroiliitis. She was diagnosed as AS and showed significant response to RTX. DAS28, ASDAS and BASDAI scores reduced. CRP level was decreased significantly. Concomitant AS and RA patients should be carefully followed and RTX treatment should be kept in mind in these patients.