Anticancer drugs routinely used in chemotherapy enter wastewater through the excretion of the non-metabolised drug following administration to patients. This study considers the consumption and subsequent behaviour and occurrence of these chemicals in aquatic systems, with the aim of prioritising a selection of these drugs which are likely to persist in the environment and hence be considered for environmental screening programmes. Accurate consumption data were compiled from a hospital survey in NW England and combined with urinary excretion rates derived from clinical studies. Physical–chemical property data were compiled along with likely chemical fate and persistence during and after wastewater treatment. A shortlist of 15 chemicals (from 65) was prioritised based on their consumption, persistency and likelihood of occurrence in surface waters and supported by observational studies where possible. The ecological impact of these ‘prioritised’ chemicals is uncertain as the measured concentrations in surface waters generally fall below standard toxicity thresholds. Nonetheless, this prioritised sub-list should prove useful for developing environmental screening programmes.