In a 15-year follow-up examination, reactive secondary amyloidosis (RSA) was found by subcutaneous fat biopsy in six out of 74 still living patients (8.1%) of an original population of 102 with erosive and seropositive rheumatoid arthritis (RA). Five of the 24 deceased patients had had RSA. Thus the 15-year incidence of RSA in RA was at least 10.9% (11/102). To study early prognostic aspects of RSA, comparison was made of 14 entry variables and the initial treatment in the RSA group (n = 11) and the control group (n = 81) respectively. At onset (< or = 6 months) of RA only serum orosomucoid, but after three years morning stiffness, ESR, serum CRP and orosomucoid were significantly worse in patients whom later developed RSA. Three out of 48 patients treated with gold sodium thiomalate and seven out of 30 treated with chloroquine developed RSA (p = 0.04). It is concluded that continuously active disease was the risk factor underlying RSA. The role of early chloroquine therapy is discussed.