The research presented is a survey of all of the identified forensic psychiatry Medium Secure Units (MSUs) within Great Britain. The study examined the numbers and nature of all escapes from these units over a 42-month period. The research focused on the relationship between the building design of the units and the nature of patient escapes. The results showed that overall numbers of patient escapes from the units was low. The average number of escapes was 3.14 per unit over the three-and-a-half-year time-span of the survey. However, the recent increases in bed numbers in medium secure units had been paralleled by a larger percentage rise in escapes. Most escapes from the units occurred from three main areas. These were the perimeter fence, the roof, and internal and external windows. The implications of the methods of escape and their relationship to the building design of MSUs were discussed and recommendations made for future building designs.