Children with juvenile rheumatoid arthritis (JRA) often exhibit fatigue and prolonged exercise recovery. Improved fitness through physical conditioning has not been a goal of standard medical or physical treatment regimens for JRA, and fitness levels of children with JRA have rarely been studied. We compared physical fitness in 20 6 to 11-year-old patients with polyarticular JRA with sex-, age-, and size-matched controls, using the Health Related Physical Fitness Test (HRPFT), a national, standardized, norm-referenced test. We correlated fitness scores with summary joint counts, and with an articular severity index (sum of joint swelling, tenderness, pain, and limited range for each child). The results showed that children with polyarticular JRA were less physically fit than normally active (noncompetitively athletic) children of the same sex, age, and size. There was no statistically significant relationship between increased joint counts, and/or disease severity scores, and reduced fitness scores. This suggests that physical fitness levels are less related to degree of “disease activity” than is often thought. We conclude that (1) a readily available, nationally standardized fitness test can be used to assess children with JRA: and (2) fitness levels and measures of disease activity do not correlate. We believe that multiple factors, perhaps including family, physician, and school concerns about potential disease exacerbation following exercise, may account for the low fitness levels observed in children with JRA.