The experience is reported concerning treatment of adult Still's disease with a combination of azathioprine and sulphasalazine. In three patients a favourable effect on the symptoms was noted. In one of these patients a year-long prednisone treatment was withdrawn and replaced by sulphasalazine. In all these cases, however, a decrease was seen in leucocyte counts to subnormal levels after the addition of sulphasalazine to a basis therapy with azathioprine 150-200 mg/d (2.1-3.3 mg/kg). The effect was only transitory in two patients, while it lasted several months in the third. In a fourth patient agranulocytosis developed after four days following the combined treatment with azathioprine 150 mg/d (2.3 mg/kg) and 250-1000 mg/d (4-15 mg/kg) of sulphasalazine, lasting four days before recovery. A later resumption of the combination therapy with these same drugs, but in a lower dosage, did not induce any acute changes in leucocyte counts. The skin rash provoked by sulphasalazine in two of the patients did not recur after desensitization. It is concluded, that this combination therapy is valuable in adult Still's disease, but that caution should be exerted during the initiation of sulphasalazine therapy. This should be monitored by daily measurements of leucocyte counts in the first weeks and preferably started by the use of a desensitising kit.