Since the last decades, an increase of reported incidence of pertussis has been observed in many countries, including Poland, despite high vaccination coverage among infants and children. Before the vaccinations era, pertussis was a major cause of morbidity and mortality among infants and young children. Currently, pertussis is increasingly reported in adolescents and adults. The objective of this paper was to present the epidemiology of pertussis in Mazovian region in Poland in years 2005-2009. In this report we analyzed retrospectively the epidemiological data collected by the Sanitary Station in Warsaw, Poland. A total of 1,455 cases of pertussis were reported in the Mazovian region of Poland in the years 2005-2009. The incidence of pertussis ranged from 2.4/100,000 (2006) to 7.9/100,000 (2008). The incidence was the highest in two groups: infants (>1 year of age; from 13.3/100,000 in 2005 to 32.7/100,000 in 2007) and teenagers (age of 10-14 years; from 11.8/100,000 in 2006 to 68.5/100,000 in 2008). The highest proportion of cases was also reported in the 10-14 years age-group (from 26.4% in 2009 to 46.0% in 2008). The number of hospitalizations due to pertussis ranged from 137 (2005) to 46 (2006), while the percentage of cases requiring hospitalization ranged from 37% (2005) to 25% (2007 and 2008). Three hundred ninety two (27%) cases of pertussis were reported among patients with negative or not confirmed history of pertussis vaccination. We conclude that there is an urgent need for booster vaccination against pertussis in adolescents and adults in Poland.