This study provides insight into the length of stay in TBS hospitals between 1990 and 2009 as well as the reason behind the developments. Results show that the length of stay increased gradually in the last 20 years with the exception of the length of stay in 1995 compared to 1994 in which a relatively large increase was seen. Findings show that the problem in the TBS-sector is due to a lack of beds in forensic psychiatric hospitals which cause waiting lists to develop. The lack of available beds was a result of an increase in the number of impositions on the TBS-orders, an increase in the average length of stay of each patient, and the wait-time for a patient to be released from the hospital after treatment is completed. This also resulted in TBS-patients experiencing long waiting times in prison before they could start their treatment in the forensic hospital. While the focus is to tackle the problems of bed shortages and long waiting times in prison, any solution attempted must not jeopardize public safety. Data were collected from available literature, meetings with experts, and analyses of two datasets: the Monitor Information System TBS-patients, and the Research and Policy Database for Judicial Documentation. Tables and figures