Ukrain is alleged to be an effective chemotherapeutic drug which causes minimal side-effects as a result of selective toxicity towards malignant cells only. We previously failed to confirm this claim and found Ukrain to be equally toxic to normal, transformed and malignant cell lines by causing a metaphase arrest. In this study we have found the antimitotic actions of Ukrain to be reversible in low doses in vitro, as shown by flow cytometry and concurrent haematoxylin and eosin stains. We hypothesize that the lack of side-effects found in vivo may be due to the lack of therapeutically effective dosages being administered, therefore enabling cells to overcome the metaphase arrest and survive.