Epidemiologic and clinical characteristics of children with disease due toBordetella pertussis in Santa Fe, ArgentinaIntroduction: Pertussis, a vaccine-preventable respiratory disease, remains a public health problem. Objective: The goal of this study is to describe epidemiological and clinical patterns of B. pertussis-caused respiratory infection over the period 2006-2010 in Santa Fe, Argentina. Methods: Inpatients and outpatients < 14 years of age, meeting pertussis case definition criteria were included. Household family contacts of confirmed cases with compatible symptoms were also surveyed. Results: 1074 patients were evaluated, 102 (9.49%) were confirmed through PCR. The proportion of confirmed cases was: in 2006, 35.5%; 2007, 21.2%; 2008, 4.9%. In 2009 and 2010 no cases were detected. 94.2% of hospitalized patients and 42.8% of outpatients were less than six months of age. Of all patients, 67.6% required hospitalization as they had a moderate to severe illness. The length of stay for these patients was over six days. 27.5% had pre-existing medical conditions, the most frequent being prematurity and malnutrition. The outcome was severe in 23.1% of cases, all of whom hadn't started the vaccination schedule. Severe pulmonary hypertension was present in five patients. Fatality rate was 4.9%. Conclusions: Pertussis mainly affected children < 6 months, non-vaccinated or with less than 3 doses. The bacterium was also detected among adults and teenagers.