Particulate contamination in small volume parenteral medications has been studied and compared with that found in a selection of large volume infusions. Particle counts in 39 commonly used small volume medications and 7 large volume infusions were performed by an automated light blockage method (HIAC) or by optical microscopy. Based on these results and a random survey of drug therapy of intensive care patients, it is concluded that the contribution of intravenous medications to the total particle load received by such patients is likely to be many times greater than from infusion fluids. Until firm evidence regarding the harmful systemic effects of drug particles is available and the manufacturing regulations adjusted appropriately, final in-line filtration of infusions immediately proximal to the intravenous cannula should be considered when drugs are being given intravenously.