Illness intrusiveness(illness induced lifestyle disruption) was investigated in 902 patients with arthritis and compared between rheumatoid arthritis(N=439) and osteoarthritis(N=463) patients. Arthritis patients were reported to perceive illness intrusiveness similar to patients with ESRD(end stage renal disease), bipolar disorder and peritoneal dialysis. Especially they were intrusive into health, work, and active recreation domains. And patients with rheumatoid arthritis were significantly more intrusive into activities, especially in diet, financial situation, family relations, other social relations, self-expression/self improvement, religious expression, and community and civic involvement. Differences in treatment regimens and age were hypothesized to account for these differences in illness intrusiveness.