[en] ⁶⁸Ga-labeled platelets could be useful for positron emission tomography (PET) studies. The labeling behaviour of human platelets labeled with ⁶⁷Ga-MPO and the viability of ⁶⁷Ga-MPO platelets were studied and compared, respectively, with ¹¹¹In-MPO. The platelet-labeling yield of ⁶⁷Ga-MPO increased with platelet concentration and with temperature and time of incubation [reaching a maximum (<20%) at 1 x 10⁹ platelets/mL, 37 deg. C, 30 min]. ¹¹¹In-MPO shows a similar behaviour, but labeling yield of platelets is significantly higher as compared to ⁶⁷Ga-MPO. Viability of ⁶⁷Ga-MPO- and ¹¹¹In-MPO-labeled platelets is maintained. The data suggest that ⁶⁸Ga-MPO is not a promising PET radiopharmaceutical for potential studies with radiolabeled platelets in clinical practice