A modified procedure for determination of metallothionein-like proteins in animal tissues.

1. The effect of low-molecular-weight substances interfering with determination of metallothionein is eliminated by precipitation of 203Hg-thionein by tannic acid. 2. In animals not exposed to metals, the mean values for metallothionein content in liver and kidney are, respectively, 0.10 and 0.18 mg/g in rats, 0.06 and 0.07 in mice and 0.12 and 0.29 in guinea-pigs, i.e. are 2-3 times lower as compared with the values obtained by the procedure not involving treatment with tannic acid.