The study evaluated the effectiveness of the combination of nimodipine and cyclosporine A vs nimodipine alone in the prevention of delayed neurologic deficit in 82 (31 plus 51) patients in whom intracranial aneurysms were clipped within 72 h after subarachnoid haemorrhage. The tests performed included examination of the neurological condition before and after operation, angiography of cerebral arteries to visualize vasospasm, and analysis of the distribution and amount of blood in the brain fluids and/or tissue according to Fisher's scale. Inclusion of cyclosporine A in the treatment was clearly beneficial for the neurological condition. While cyclosporine A did not appear to produce a statistically significant improvement as evaluated by the chi-square test, a positive result was obtained following analysis of the correlation coefficients after Pearson in combination with the logistic log-linear regression analysis. The results argue against the utility of the chi-square test for verifying clinical data obtained in a limited number of patients.