The present in vitro and in vivo experiments were undertaken to clarify the genotoxic potential of the hydroxyanthrachinone aloeemodin which can be found in different plant derived products for therapy of constipation. The results demonstrate that aloeemodin is able to induce mutagenic effects in vitro. Positive results were obtained in the chromosomal aberration assay with CHO cells, as well as in the Salmonella reverse mutation assay (frameshift mutations in strains TA 1537, TA 1538 and TA 98). No mutagenic potential of aloeemodin, however, was observed in the gene mutation assay with mammalian cells in vitro (HPRT assay in V79 cells). Each assay was performed in the presence and absence of an extrinsic metabolic activation system (S9-mix). In in vivo studies (micronucleus assay in bone marrow cells of NMRI mice; chromosome aberration assay in bone marrow cells of Wistar rats; mouse spot text [DBA/2JxNMRI]) no indication of a mutagenic activity of aloeemodin was found. Information about a possible reaction of aloeemodin with DNA was derived from an in vivo UDS assay. Hepatocytes of aloeemodin-treated male Wistar rats did not show DNA damage via repair synthesis. All these data suggest that aloeemodin is able to interact with DNA under certain in vitro conditions. However, in vivo the results that were negative did not indicate a genotoxic potential. Therefore, it may be assumed that a genotoxic risk for man might be unlikely.