Research on the benthic oligochaete worm Branchiura sowerbyi is carried out as part of a project to develop a set of sediment toxicity tests. In the report the choice of B. sowerbyi as a potential test species is illustrated. An interim toxicity test method is presented which is based on experiments with the model compound ethyl-chloropyriphos. B. sowerbyi can be cultured in the laboratory. An interim culture method is reported as well as the experiments carried out to improve the culture method. Further research with other model compounds in order to improve the toxicity method will be reported in a coming report.