Objectives To describe disaster preparedness among chronically ill patients and to examine how differences in health, functional, and disability conditions are associated with disaster preparedness, focusing on rheumatoid arthritis (RA) patients with various functional and disability levels. Methods In 2007, 1,477 members of a nationwide RA patient group in Japan who lived in municipalities affected by natural disasters between 2004 and 2006 were asked to participate in a questionnaire survey. Three medical preparedness indicators, namely, medication stockpiles, the carrying of medications, and the carrying of prescription/ treatment records, and three general preparedness indicators, namely, having emergency packs, emergency communication plans, and emergency evacuation plans, were used as dependent variables. Multivariable logistic models were applied to examine the associations of health-related vulnerability variables with the preparedness variables. Results Of the 553 subjects included into the analysis, only one-half had taken medical preparedness measures and only one-quarter had taken general preparedness measures. Although physical disability and poorer functional level were associated positively with the medical preparedness, those with poorer perceived health were less likely to carry medications and prescription/treatment records, and those receiving the highest long-term care levels were less likely to carry medications than their healthier counterparts.Conclusions Among the population of chronically ill RA patients surveyed, disaster preparedness was insufficient, and their preparedness status varied with health, functional, and disability conditions. We suggest that policy-makers should give careful thought to the targets they set for disaster preparedness.