Plasma, intraleukocytic and intraerythrocytic zinc, cooper, and magnesium levels of patients with rheumatoid arthritis who were and were not receiving tenoxicam have been determined. The results of the patients who were not receiving tenoxicam are as follows: plasma levels (mu mol/l): zinc 15.4 +/- 0.41 (arithmetic mean +/- standard error of the mean), copper 21.2 +/- 0.82, magnesium 1,120 +/- 15.8. Intraleukocytic levels (ng/10(6) cells) zinc 17.5 +/- 2.64, copper 0.451 +/- 0.064, magnesium 60.0 +/- 5.68. Intraerythrocytic levels (mu g/10(10) cells): zinc 5.20 +/- 0.61, copper 2.64 +/- 0.44, magnesium 66.1 +/- 4.87. There was no significant difference between all 3 element levels of patients who were or were not receiving tenoxicam. Plasma, leukocyte, and erythrocyte zinc levels of both groups of patients were lower (p < 0.001), copper levels were higher (p < 0.001) than those of healthy subjects. Plasma and leukocyte magnesium levels of both groups of patients and only erythrocyte magnesium levels of patients receiving tenoxicam were higher (p < 0.01) than those of healthy control group.