To evaluate the extent of food allergy/intolerance in rheumatoid arthritis, an elemental (hypoallergenic) diet was studied in a controlled, double-blind pilot study. Ten patients were allocated to an experimental group and 7 to a control group. The patients in the experimental group received an elemental diet for 3 weeks, whereas the patients in the control group received a control soup consisting of milk, meat, fish, shellfish, orange, pineapples, tomatoes, peas and flour of wheat and corn. During the 4th week of the study the patients in both groups resumed their regular diet. A significant improvement was found in the number of tender joints (p = 0.04) in the experimental group, whereas improvement was found in the erythrocyte sedimentation rate (ESR) (p = 0.03) and in the thrombocyte count (p = 0.02) in the control group. Three patients in the elemental diet group and 2 patients in the control group improved in all of the measured disease variables during the dietary treatment period. There was no significant difference in disease activity variables between the two groups. These results suggest that some RA patients may respond to the elimination of offending food items. However, the results do not encourage treatment with an elemental diet in unselected RA patients.