The antecubital fossa venipuncture site in frequent blood donors can become scarred or "dimpled" and colonized with surface and deep bacteria that are not sterilized by standard iodophor preparation techniques. These microorganisms can be introduced into blood or platelets at the time of donation. Recent advances that permit the prolonged storage of platelets at room temperature before transfusion allow proliferation of these contaminating bacteria, particularly gram-positive microorganisms. Documented are three episodes of platelet contamination with gram-positive organisms and four cases of sepsis in recipients of these platelets, which were obtained through the "dimpled" site of a single donor and stored for at least 80 hours at 22 degrees C before transfusion. In contrast, platelets harvested from this donor's "dimpled" site and stored for not more than 50 hours were transfused to 25 patients without complication. Therefore, the extended storage of platelets at 22 degrees C prior to transfusion demands strict awareness of any possible sources of extrinsic contamination, since gram-positive bacteria can proliferate under these conditions and result in infectious complications in recipients.