An outbreak of listeriosis occurred in the Swindon area of the UK in autumn 2003. Five cases were detected in pregnant women. Four of these women were thought to have eaten prepacked sandwiches from a retail outlet in one particular hospital. Sampling at the supplier detected Listeria monocytogenes, which was indistinguishable on molecular testing from the patients" isolates. Recent changes in UK food legislation should help diminish the risk of further outbreaks/ cases such as ours occurring. (R.A.)