Background - Most anxiety/depression is not effectively treated. Aims - Open evaluation of a free clinic giving immediate computer-aided cognitive–behavioural therapy (CBT) self-help plus brief advice from a therapist. Method - Test of outcome of self-referrals who used one of four computer-aided CBT systems for depression, phobia/panic, general anxiety or obsessive–compulsive disorder. Results - The equivalent of one full-time clinician managed 355 referrals over a year. Of the 266 who had a screening interview 79% were suitable. Completers and non-completers of computer-aided CBT had similar pre-treatment features, with very chronic, moderately severe problems. Completers of the computer-aided self-help had a mean total of an hour’s live therapist support over 12 weeks. They improved significantly and clinically meaningfully with three of the four systems and felt ‘fairly satisfied’. Improvement resembled that in controlled and other trials of computer-aided CBT. Conclusions - Computer-aided self-help is a ‘clinician extender’that greatly cuts per-patient therapist time without impairing improvement. It could reduce the per-patient cost of CBT.