Platelet concentrates stored for 7 days in 50 ml of plasma in both thin film and enlarged variations of the standard 5‐day CLX plastic bags were evaluated for pH maintenance and in vivo viability by two laboratories working independently. 51Cr‐labeled platelets were reinfused into normal volunteers at the end of storage and recovery and half‐life calculated. The pH was maintained well; < 10 percent of units fell below 6.0 at 7 days. Mean 7‐day recovery for both laboratories was 43.6 ± 11.6 percent in the thin‐film bag and 45.4 ± 8.52 percent in the enlarged bag, compared with 43.6 ± 8.8 percent at 5 days in the 5‐day plastic licensed bag. After 7 days storage the half‐ life was 3.6 ± 0.9 days in the thin‐film bag and 3.7 ± 0.6 days in the enlarged bag, compared with 3.6 ± 0.5 days in the previously licensed CLX plastic bag after 5 days. Thus, platelet viability was maintained well at 7 days of storage in both of the container variations that allowed increased gas exchange.