The stability of fluorouracil when prepared and stored in plastic containers used for continuous infusion in home therapy was studied. Fluorouracil was diluted with 5% dextrose injection. Samples were stored for 16 weeks at 5 degrees C and room temperature in polyvinyl chloride drug reservoirs and at 5 degrees C in elastomeric balloons used in a disposable drug pump. Periodically, samples were tested by a stability-indicating high-performance liquid chromatography (HPLC) assay. At 5 degrees C, there was no significant degradation. At room temperature, there was a progressive increase in fluorouracil concentration, presumably because of evaporation of water. A 10% change in the fluorouracil concentration over 55 days was predicted. Fluorouracil is stable in 5% dextrose injection for at least 16 weeks when stored at 5 degrees C in the two types of containers studied.