Haemophilus influenzae type b (Hib) is a leading cause of childhood pneumonia and bacterial meningitis; pneumonia accounting for most of the burden in low-income countries. Uncertainty over Hib disease burden and scarcity of data on vaccine effectiveness has delayed adoption of Hib vaccine in some parts of Asia. In June 2009, the Government of Bangladesh introduced Hib conjugate vaccine into the National Expanded Program on Immunization (EPI) as a pentavalent formulation. We assessed the impact of this introduction on purulent and confirmed Hib.