The guinea pig maximization test was used to study the sensitizing potential of Podophyllum lignans; 0.5% of each drug in propylene glycol was used for induction and 0.01%, 0.05%, 0.1% and 0.5% preparations for topical challenge. The 0.1% and 0.5% preparations caused non-allergic toxic reactions associated with the cutaneous destructive influence of these drugs; allergic responses did not occur.