Data were collected concerning 314 internal arteriovenous fistulas created in 242 adult patients (92 women and 150 men). The immediate failure rate for the various techniques used ranged from 7-7 to 12-0 per cent, except for ulnar fistulas which had a rate of immediate thrombosis of 20-7 per cent. Survival rates were significantly lower for patients submitted to a combined therapy of dialysis and kidney transplantation when compared with patients treated with dialysis alone. The probability of survival of an arteriovenous fistula was lower in women than in men but the difference was significant only in patients undergoing transplantation. Survival rates at 2 years in dialysed patients were 87-6 per cent for distal radial-cephalic side-to-side fistulas, 100 per cent for radial-cephalic end-to-side fistulas located in the mid-forearm, 78-5 per cent for radial-cephalic end-to-side fistulas created near the wrist, 53-1 per cent for distal radial-cephalic end-to-end fistulas and 60-9 per cent for ulnar fistulas. Thrombosis was responsible for 87-2 per cent of 109 late failures. The incidence of infection was 1 case/11 patient years of haemodialysis.