1. Eight hundred and forty-six patients with pain in one or two joints of the hip, knee, ankle or wrist participated in a randomised double-blind trial to compare the efficacy, tolerability and effect on quality of life of diclofenac sodium slow release (DSR) 100 mg daily and a combination of dextropropoxyphene 180 mg and paracetamol 1.95 g daily (D&P). Health status or quality of life was measured using the Nottingham Health Profile (NHP) questionnaire. 2. Pain as measured by a visual analogue scale (VAS) showed 8% greater pain reduction with DSR as compared with D&P (P less than 0.05). Physical mobility as measured by the NHP improved by 13% more with DSR as compared with D&P (P less than 0.01). Energy, sleep, social isolation and emotional reactions did not differ significantly between the two treatment groups, but both treatment groups showed improvement during the trial. More D&P patients as compared with DSR patients reported problems with their job of work (P less than 0.05), and time lost from work (P less than 0.05). 3. Patients on D&P suffered an excess of tiredness or sleep disturbance (50 vs 21, P less than 0.01) whilst patients treated with DSR had an excess of abdominal or epigastric pain or indigestion (40 vs 18, P less than 0.01). 57 patients were withdrawn from DSR and 65 from D&P.