Computer technology has been applied to psychiatry and psychotherapy for four main purposes: as a diagnostic aid, for computer-assisted instruction, to aid cognitive rehabilitation, and for computer-mediated psychotherapy (CMP). The first and second applications have proved highly useful in some psychiatric domains, but CMP is at a preliminary stage and remains controversial because little evaluation data is available. The questions addressed in this paper are: Can psychologic computer software cope with emotional and behavioural dysfunctions? To what extent can the use of computers help the patient recover? The authors review experiences in this area and discuss the dangers, possible drawbacks, major objections and limits of CMP. They also examine the possibility that computer applications may help in the understanding of psychotherapy. Finally, they address some ethical issues in the application of this technique.