Anaemia is a common manifestation of juvenile rheumatoid arthritis (JCA). We have evaluated 26 JCA patients with anaemia and compared their laboratory parameters to those without anaemia. In the patients with anaemia, activation criteria such as erythrocyte sedimentation rate (ESR) and CRP were significantly higher than in those without anaemia. Anaemia was present in all systemic JCA patients and was present in 42% and 78% of the oligoarticular and poly-articular types, respectively. Serum iron levels and transferrin saturations were low in all, whereas serum iron-binding capacities of the patients were normal. Mean ferritin level was 249pg/1 (range 8.46-1000pg/1). There was a significant correlation between ferritin levels and CRP and ESR (r=0.48 and r=0.55 respectively) (both p < 0.05), Epo levels were normal. Twelve (60%) of the bone marrow aspiration specimens stained positive for iron whereas 40% stained negative; there were also changes suggestive of myelodysplasia. Sideroblasts were also decreased in number. Thus, in these patients iron is not sufficiently transferred to the erythroid series and/or cannot be used by erythroblasts, accompanied by a possible absolute iron deficiency. Thus we suggest that the iron in JCA tends to be stored in the form of ferritin, not in an accessible form and impaired metabolism along with other factors are effective in the anaemia of JCA.