The Mental Capacity Act 2005 was partially implemented in April 2007. Doctors should be aware of the Act and what implications it has on their clinical practice. This survey looked at the knowledge of physicians and psychiatrists regarding assessing capacity within the Act by means of a questionnaire. The results showed that 100% of physicians and 70% of the psychiatrists answered questions wrongly in the questionnaire. Also, 97% of physicians and 70% of psychiatrists did not have some aspects of knowledge about capacity. Statistically significant differences in responses between physicians and psychiatrists were in relation to their knowledge of the existence and implementation of the Act. Answers were related to active schizophrenia, weighing up pros and cons, and recent assessment of incapability in relation to being by definition incapable. This study shows that psychiatrists do slightly better in answering questions about the Mental Capacity Act 2005 and about capacity when compared with physicians, however both groups could improve their knowledge. With the full implementation of the Act in October 2007, this study shows the urgency and importance of training in the area of capacity for all doctors.