The Surgical Site Infection (SSI) has been pointed as one of the most important infection sites. This study aimed to determine the surgical site infection incidence during hospitalization and the impact of notification after discharge through two methods. This prospective study was carried out in the digestive system surgery service (DSS) of two general hospitals of São Paulo, in the period from August, 2001 to March, 2002. Incidence levels of 6.7% and 4.5% were notified in the institutions A and B respectively. The incidence of SSI after discharge in the institution A was 27% and 13.4% in the institution B. Surveillance after discharge evidenced global rates of 33.7% and 17.9% for institutions A and B respectively. The rates of infection increased 5.02 and 3.98 times respectively in institutions A and B.