Delivering psychotherapy by videoconference could significantly increase the accessibility of empirically validated treatments. The aim of this study was to compare the effectiveness of cognitive-behavior therapy (CBT) for panic disorder with agoraphobia (PDA) when the therapy is delivered either face-to-face or by videoconference. A sample of 21 participants was treated either face-to-face or by videoconference. Results showed that CBT delivered by videoconference was as effective as CBT delivered face-to-face. There was a statistically significant reduction in all measures, and the number of panic-free participants among those receiving CBT by videoconference was 81% at post-treatment and 91% at the 6-month follow-up. None of the comparisons with face-to-face psychotherapy suggested that CBT delivered by videoconference was less effective. These results were confirmed by analyses of effect size. The participants reported the development of an excellent therapeutic alliance in videoconference as early as the first therapy session. The importance of these results for treatment accessibility is discussed. Hypotheses are proposed to explain the rapid creation of strong therapeutic alliances in videoconferencing.