[en] Interaction of a series of ^99mTc-radiopharmaceuticals with human blood proteins was investigated from two aspects: total protein binding, and specificity of binding to certain classes of proteins. After in vitro labelling of human sera with ^99mTc-radiopharmaceuticals, total protein binding was determined for thirteen ^99mTc-compounds (complexes of: HMPAO, GH, PAHIDA, MAG₃, DTPA, PYP, MDP, DPD, EHIDA, IODIDA, Phytate and both complexes of DMSA) by a precipitation method (perchloric and trichloroacetic acid), dialysis and ultrafiltration. (author)