Undetected posttraumatic stress disorder (PTSD) has serious adverse consequences. General practitioners (GPs), psychologists, and psychiatrists all have an important part to play in recognising, assessing, and treating individuals with PTSD. The knowledge level of these clinicians was investigated using a purpose-designed PTSD Knowledge Questionnaire. Respondents included 59 GPs, 56 psychologists, and 39 psychiatrists who scored an average of 68%, 77%, and 79% of questions correct, respectively. As expected, GPs' knowledge was significantly lower than the other two groups, but no group demonstrated excellent knowledge and the knowledge of individual clinicians varied greatly. Strengths and deficits in knowledge areas are discussed in terms of the potential impact on individuals with PTSD, and implications for professional training. (Contains 5 tables.)