To find ways of predicting survival or death in cases of severe shock, arterial blood pH and gases, vital signs, and the half-life of activity in the enzymes guanine deaminase, aspartate aminotransferase (AST) and alanine aminotransferase (ALT), were studied in 24 patients. The mean arterial blood pH (+/- SD) in survivors was 7.325 +/- 0.092 while that in non-survivors was 7.108 +/- 0.251 (p less than 0.05). The mean half-life of guanine deaminase in survivors was 19.8 +/- 3.3 hours, while that in non-survivors was 58.6 +/- 11.8 hours (p less than 0.001). When the screening values were set at 7.190 for the arterial blood pH and 36 hours for the half-life of guanine deaminase activity, the 'validity' (sensitivity plus specificity) for the combination of the two tests was 1.88. The values may be useful for the prognosis of survival in severe shock patients.