The forehead tissue temperature (FT-T) and the sole tissue temperature (ST-T) were measured and recorded by a deep body thermometer (Terumo Corp.) during open heart surgery. The changes in FT-T and ST-T after cardiopulmonary bypass (CPB) showed two characteristic patterns; the convergence pattern and the dissociation pattern. It is said that the dissociation pattern can notes a poor peripheral circulation. The deverging point of the two patterns was studied in 65 patients with acquired cardiac disease. We divided the patients into two groups taking 3.5 degrees C of the FT-T and ST-T difference (DT) after 2 hour weaning from CPB. The number of the patients in convergence group (group I) was 42, and that in the dissociation group (group II) was 23. The two groups were compared with the DT and the time required for the rise in each temperature from CPB rewarming to CPB weaning. There was no intergroup difference in the DT when the FT-T began to rise upon CPB rewarming. However, the DT was 3.8 +/- 2.3 (mean +/- SD) degrees C in group I and 7.1 +/- 1.8 degrees C in group II when the ST-T began to rise, and 4.2 +/- 2.5 degrees C in group I and 6.9 +/- 1.4 degrees C in group II when the FT-T reached its peak; the figures were significantly lower in group I (P < 0.01). The time required for the rise in ST-T was significantly shorter in group I (14.8 +/- 17.1 min) than in group II (25.8 +/- 14.7 min).(ABSTRACT TRUNCATED AT 250 WORDS)