[en] A two steps method of direct labelling of anti-human hepatoma monoclonal antibody fragment HAb18 is investigated. Stannous chloride and sodium bisulfite is used as reducing agents of ¹⁸⁸ReO₄^- and antibody fragment respectively. The effects of reduction conditions of ¹⁸⁸ReO₄^- bio-thiol and antibody on the labelling efficiency is evaluated in detail. The results show that labelling efficiency, numbers of thiol and immunoreactive fraction reached up to 85%-893%, 2.4/molecule and 0.91 respectively. The stability of labelling compounds keep much better in vitro. The biodistribution in normal and nude mice demonstrates that ¹⁸⁸Re-Fab' (¹⁸⁸Re-F(ab')₂) is cleared rapidly from the blood and mainly from kidney, and tumor has significant uptake