Despite of recommendations, influenza vaccine (IV) coverage among healthcare workers remains low in many countries. We aimed in this study to assess the main reasons leading to flu vaccine acceptance and decline among Tunisian healthcare workers through a study of knowledge, attitudes and practices towards influenza immunization. It was a cross sectional study conducted in Tunisian primary and secondary healthcare facilities from March to May 2019. Health professionals were enrolled according to a self-weighted multistage sampling. A face to face questionnaire was administered to participants. Reasons leading to IV acceptance and decline were assessed through open-ended questions. A total of 1230 HCWs were included in the study with a mean age of 44.5±9.3 years and a sex-ratio (M: F) of 0.25. Among participants, 43.1% (95%CI: [40.3-46.0]) were willing to receive the flu vaccine if recommended to caregivers and provided for free. According to participating healthcare workers, the main three reasons leading to vaccine acceptance were: self-protection (73.8 % [71.3-76.3]) and family and patients’ protection (49.2% [46.4-52.0] and 28.2% [25.8-30.7] respectively). Regarding reasons leading to IV decline, fear of the vaccine side effects (48.0% [40.3-46.0]), feeling not concerned by the flu vaccine (31.8% [29.3-34.4]) and doubt about vaccine efficacy (31.6% [28.8-34.3]) were the most frequent cited reasons. Less than half of participants were willing to receive the IV. Fear of flu vaccine side effects was the most frequently reported reason leading to vaccine decline. Health authorities should thus organize regular training sessions in healthcare facilities aiming to educate caregivers about IV composition and safety.