This study assessed factors that could predict dentists’ knowledge, attitudes and behaviour towards hepatitis B virus (HBV). A total of 300 dentists in Tehran, Islamic Republic of Iran were surveyed and their demographic, educational and office characteristics were analysed in relation to their scores on knowledge about HBV, self-reported attitudes towards treating people infected with HBV and actual behaviour towards treating simulated HBV-positive patients. Having a Master’s degree, faculty membership, taking ≥ 3 continuing education courses, wearing eye-shields, spending more time on preparing dental units and higher self-confidence about knowledge predicted better knowledge. A positive attitude was associated with having attended more courses and working in group practice. The number of courses and a shorter dental unit preparation time positively affected dentists’ behaviour.