Many issues frame the question, "What expiration date should be be applied to a multiple-dose medication vial after it has been first used?" Current recommendations; the use of preservatives; and the potential for microbial, fungal, and viral contamination are discussed. Selected epidemiological studies, emphasizing that multidose vial (MDV) contamination does in fact occur; are cited. The use of MDVs in many settings is not an acceptable practice and should be discontinued. The personal use of an MDV by a single individual is deemed acceptable as is the use of MDVs for aseptic compounding within a laminar flow hood.