The present cross-sectional study was conducted in the Department of Medicine, Mymensingh Medical College Hospital, Mymensingh from December 2009 to November 2010 to find out the association of iron deficiency, in anaemia with rheumatoid arthritis and to find a sensitive and less invasive marker to differentiate iron deficiency anaemia from the anaemia of chronic disease. A total of 45 patients of rheumatoid arthritis were provisionally included in the study. Of them, 12 patients were excluded as they did not allow for aspirating the bone marrow, leaving 33 patients to complete the study. The mean age of the patients was 42.6 years (22-66 years) with female to male ratio being roughly 3:1. Majority (97%) of the patients presented weakness followed by 78.8% dizziness, 54.5% palpitation, 24.2% pallor, 12.1% breathlessness, another 12.1% smooth tongue and 6.1% nail change. About 79% of the patients were positive for RA test and nearly 70% of patient had moderate anaemia. The mean serum ferritin was significantly reduced in patients with hypochromic with or without microcytic anaemia than that with normocytic normochromic anaemia (p<0.001). While total iron binding capacity was found to be significantly increased in patients with iron deficiency anaemia than that in patients with anaemia of chronic disease (p<0.021). The serum iron level was considerably reduced in the former group than that in the later group (p<0.066). Bone marrow iron grading revealed 48.5% of the patients with iron depleted and 51.5% with iron repleted. Serum ferritin level of patients with iron depleted bone marrow was significantly decreased than that in patients with iron repleted bone marrow (p<0.001). Serum iron level of the former group was also reduced than that of the later group (p<0.133). Total iron binding capacity was significantly raised in patients with iron depleted group than that in patients with iron repleted group (p<0.001). The study finds that anaemia of chronic disease and iron deficiency anaemia frequently coexist in patients with rheumatoid arthritis and serum ferritin and total iron binding capacity are considered good indicator for differentiating iron deficiency anaemia from the anaemia of chronic disease. Serum iron levels will not help for differentiating.