Resympathectomy of the upper extremity. Resympathectomy was performed in 27 patients (eight bilaterally) with ischaemic hand phenomena. An extended operative technique, resecting parts of the second and third intercostal nerves and their surrounding tissue, was used. In all 35 procedures the posterior extrapleural approach was used. Follow-up was from 3 to 12 years. Only the sympathetic ganglia had been removed during the previous surgery by the axillary approach (67 per cent of these patients had had a transient response for between 6 months and 2 years; 33 per cent had had no response at all). A direct subjective improvement was seen after 27 of the 35 reoperations (77 per cent). In 14 patients continuous wave Doppler ultrasound studies were available and showed a significant increase in peak forward frequency after operation (P less than 0.001). From these data it may be concluded that it is possible to obtain a resympathectomy effect, but reoperation should be reserved for special cases for whom survival of digits is essential. 