Based on the outcome in 116 consecutive patients who were subjected to early aneurysm operation combined with additional nimodipine treatment, and who were controlled by transcranial Doppler (TCD) sonography, a morbidity and mortality analysis was performed. Of the 84 patients who preoperatively were in Hunt & Hess grades III, 79 patients (94%) were considered to show a favourable (good-fair) late recovery, while one patient (1%) had a poor outcome, and four patients (5%) died. Of the 32 poor condition patients (H & H IV-V), 17 (53%) showed a favourable recovery, while seven (22%) had a poor outcome, and eight patients (25%) died. Altogether, 20 patients (17%) had an unfavourable (poor-dead) outcome. Only two of these patients showed delayed ischaemic deterioration, one as a consequence of a secondary occlusion of perforating branches from the basilar artery and one with decompensated vasospasm after the evacuation of an epidural haematoma and a longlasting severe systemic hypotension; both these patients died. In another six of the patients with an unfavourable outcome, this was mainly related to a complicated surgery. The unfavourable outcome was related to primary brain damage produced by the subarachnoid haemorrhage (SAH) in ten patients and in two patients to internal medical complications. In addition to the two patients who died following delayed deterioration, secondary neurological dysfunction occurred in 11 patients. In 10 of these patients transient neurological dysfunction was attributed to vasospasm or to a combination of vasospasm with intraoperative or postoperative complications. One further case of delayed deterioration was attributed to secondary occlusion of the internal carotid artery after a complicated operation.(ABSTRACT TRUNCATED AT 250 WORDS)