An increasing concentration of heavy metals in the environment is a serious problem for human and animal health protection and production of foodstuffs in many countries around the world. The aim of this paper was to suggest a new heavy metal biosensor based on interaction of metals (cadmium and zinc) with metallothionein, which belongs to group of intracellular, high molecular and cysteine-rich proteins binding heavy metals, using adsorptive transfer stripping (AdTS) differential pulse voltammetry (DPV). Primarily, we studied the electrochemical behaviour of MT on the surface of hanging mercury drop electrode by AdTS DPV. Perfect coverage of the electrode surface -- forming of the surface assembled monolayer -- was reached at time about 240 s for 1 uM protein concentration. The detection limits of the selected heavy metals (cadmium and zinc), which were analysed in the presence of the basic electrolyte -- 0.5 M NaCl (pH 6.4), were 250 fmole and 340 fmole in 5 ul drop, respectively. In addition, we applied the biosensor to analyse heavy metals in human body liquids (human blood serum and human urine) and beverages.