The capability of vinegary pickle (2% solution of acetic acid) as a decontaminant for mushrooms has been studied. The complete sporocarps of Xerocomus badius, Suillus luteus and Lepista saeve in dry weight, the native state and after defrosting were investigated. The mushroom samples gathered in forest ecosystems were contaminated by the post-Chernobyl radiocesium. The activity concentrations of 137Cs were determined by the semiconductor gammaspectroscopy. It was proved that the reduction in activity has been affected by the frequency of replacement of acetic acid. However, the number of replacements is limited due to a change of the mushroom consistency. The vinegary pickle is already effective after the first treatment, i.e. the activity in the dry weight was reduced by 73%, and in the native state by 59%. The radiocesium activity follows an exponential curve with the exponents of 0.766 (the dry weight with the values exceeding the maximum permissible level of contamination), 0.266 (the dry weight with low activities) and 0.040 (mushrooms in the native state with the activities near the maximum permissible level of contamination) for the repeated effect of the fresh solution of acetic acid.