To see if citrate-phosphate-dextrose-adenine-two (CPDA-2) anticoagulant-preservative had an effect on the viability of platelets, we studied autologous in vivo recovery and survival in humans for platelet concentrates prepared from six units of blood drawn into CPDA-2 and compared them to six units drawn into citrate-phosphate-dextrose (CPD). These units were prepared from whole blood held at room temperature for 8 hours after collection and were then stored for 3 days at 22 +/- 2 degrees C. The recovery for platelets preserved in CPD was 39.0 +/0 4.8 percent and for platelets preserved in CPDA-2, 32.5 +/- 4.4 percent. The difference was not significant (p greater than 0.10). In order to estimate population differences, in vitro effects on in vivo viability were also evaluated. Six in vitro variables were studied but only pH at 72 hours (r = 0.77), platelet count (r = 0.64), and morphology score (r = 0.66) correlated to recovery. Only pH at 72 hours significantly influenced recovery (p = 0.007). By adjusting for individual pH differences, mean recovery for platelets stored in CPD was 37.5 percent, and for platelets stored in CPDA-2, 34.0 percent. The mean lifespan was 6.7 +/- 0.7 days for platelets preserved in CPD and 6.1 +/- 1.0 days for those preserved in CPDA-2. Although hemostatic function was not studied, these data support in vitro observations that platelets preserved with CPDA-2 are not different from platelets preserved with CPD, even after 8-hours of storage of whole blood at room temperature prior to platelet concentrate preparation.