Patients with rheumatoid arthritis were tested on a number of psychological variables, including locus of control, cognitive style, general psychopathology and problem solving. Demographic data were also noted, including social supports and life events. Those people whose serum was positive for rheumatoid factor showed a negative style of thinking, particularly in relation to their illness, and they were more likely to believe in powerful external forces. There were no differences between these patients and those who did not have rheumatoid factor on the general measure of psychopathology, except that the positive group experience more phobias. This latter result is in contradiction to previous findings, and a number of possible reasons are discussed.