Although human visceral leishmaniasis (VL) is a notifiable disease in Italy, there is evidence that the actual number of cases is far higher than that notified. A programme for active surveillance of VL in the 14 Italian endemic regions was launched by the Istituto Superiore di Sanità. We report data collected during a 3-year period of active surveillance in Campania, a south Tyrrhenian region covering 4.5% of the Italian territory. Out of 120 clinically suspected cases referred to medical and diagnostic references centres, there were 52 confirmed VL cases (17.3/year), i.e. 10-fold more than previously notified. Most of the infection sites were in rural areas or peripheral districts of towns in hilly parts of Naples province. An epidemic cluster of 10 cases was identified in a microfocus of Caserta province. The biochemical analysis of 23 Leishmania stocks showed a zymodeme composition indicating Campania as an old and well-established focus of VL. The data obtained emphasize that the present notification system for VL in Italy is inadequate.