A number of different methods exist that use chromium-51 to determine platelet survival and recovery. A 1986 article in TRANSFUSION described the recommended methods for conducting such studies in the hope of standardizing methodology and permitting interlaboratory comparison of results. The results obtained with the recommended method have been compared with those of our previous method. With the new method, recovery of fresh random-donor platelets prepared in polyolefin bags was 76 ± 6 percent with a survival of 9.3 ± 2.8 days (n = 4). After 5 days of storage, these values were 67 ± 8 percent and 7.8 ± 1.9 days. Similar values were obtained for fresh and stored platelets collected on automated cell separators. However, when our previous (pre-1986) method of evaluation was used, recovery of fresh platelets in the polyolefin bags was 56 ± 11 percent, and survival was 8.6 ± 1.3 days. The 5-day values were 36 ± 5 percent and 6.9 ± 2.7 days. These values are significantly lower (p<0.05) than those obtained with the newer method, but they are in agreement with those previously reported for other techniques. Thus, the new method consistently gives higher values, possibly as a result of a less harmful labeling procedure.