This paper presents the results of study on the toxic action mechanism of organic derivatives of tin (IV) on black lipid membrane (BLM) as a model of cell membrane. Trimethyltinchloride, tripropyltinchloride, tributyltinchloride, triphenyltinchloride, dimethyltindichloride, dipropyltinchloride, dibutyltin- dichloride, diphenyltindichloride were tested. The compounds were selected to determine the role of their structural elements in the mechanism studied. The measurements were made for the concentrations of investigated compounds ranging from 0 to 12x 10-7 mol/L, i.e. within the range of toxic concentrations, causing the BLM depolarisation. The effects of compounds studied on BLM were strongly dependent on their concentration and structure, which the trans- membrane-potential measurements of model-membrane depolarisation (dynamics and extent) showed the most evidently. The efficiency of the interaction between the black lipid membrane and the tin (IV) derivatives increased as follows: dialkyl > trialkyl > diphenyl > triphenyl. The compounds studied were recognised as having the lipophilic properties-crucial for modification of model and biological membranes.