Despite the benefits of vaccination for health care workers (HCWs), uptake of recommended vaccinations is low, particularly for seasonal influenza and pertussis. In addition, there is variation in uptake within hospitals. While all vaccinations recommended for HCWs are important, vaccination against influenza and pertussis are particularly imperative, given HCWs are at risk of occupationally acquired influenza and pertussis, and may be asymptomatic, acting as a reservoir to vulnerable patients in their care. This study aimed to determine predictors of uptake of these vaccinations and explore the reasons for variation in uptake by HCWs working in different hospital wards. HCWs from wards with high and low influenza vaccine uptake in a tertiary pediatric and obstetric hospital completed a questionnaire to assess knowledge of HCW recommended immunizations. Multiple logistic regression was used to determine predictors of influenza and pertussis vaccination uptake. Of 92 HCWs who responded, 9.8% were able to identify correctly the vaccines recommended for HCWs. Overall 80% of respondents reported they had previously received influenza vaccine and 50.5% had received pertussis vaccine. Independent predictors of pertussis vaccination included length of time employed in health sector (P