Diarrheic toxins, especially okadaic acid, are detected nearly every year in mussels on French coasts. The monitoring network determines the toxicity of these shellfish by using a mouse test now considered unsatisfactory from an ethical point of view. Two alternative methods have been investigated: the daphnia test, for which there is a standardized method used routinely in ecotoxicology, and a cytotoxicity test on the KB cell line developed for this study. Using the same samples, the results of these two tests were compared with those obtained by chemical analysis (HPLC okadaic acid assay) or the mouse test. Linear regression studies showed that results for the two bioassays were well correlated with those for HPLC or the mouse test.