Cognitive behavioral bibliotherapy for panic disorder has been found to be less effective without therapist support. In this study, participants were randomized to either unassisted bibliotherapy (n=20) with a scheduled follow-up telephone interview or to a waiting list control group (n=19). Following a structured psychiatric interview, participants in the treatment group were sent a self-help book consisting of 10 chapters based on cognitive behavioral strategies for the treatment of panic disorder. No therapist contact of any kind was provided during the treatment phase, which lasted for 10 weeks. Results showed that the treatment group had, in comparison to the control group, improved on all outcome measures at posttreatment and at 3-month follow-up. The tentative conclusion drawn from these results is that pure bibliotherapy with a clear deadline can be effective for people suffering from panic disorder with or without agoraphobia. © 2010.