This study evaluated the proportion of food samples, examined by the Italian Istituti Zooprofilattici Sperimentali (Experimental Zooprophylactic Institutes) in the years 2000-2005, positive for Campylobacter and Listeria. A correlation was found between food samples found positive for Listeria in the years 2002-2005 and the number of hospitalisations for Listeria illness in the same years (as reported in hospital discharge abstract forms). This confirms that attention should be given in the evaluation of phenomena known to be under reported and for which data are collected and analysed by different methods.