Background. Studies of cognitive behavioural therapy delivered by computer (cCBT) show clinical efficacy for treating anxiety and depression, but have not focused on barriers to uptake. Potential barriers include adverse consequences, accessibility and acceptability. Method. An integrated systematic review was conducted of quantitative and qualitative studies and surveys from multiple electronic databases where computers delivered cCBT for anxiety or depression. Results. Substantial numbers of potential participants are lost prior to trials commencing with little explanation. Among trial participants, drop-outs may be higher in the cCBT groups (odds ratio 2.03, 95% confidence interval 0.81– 5.09). Only a median of 56% completed a full course of cCBT and personal circumstance was a more common cause of drop-out than difficulties with the technology or social background. Risk was rarely assessed in the majority of programs. Significant staff time was needed to support clients. Therapists were more negative about cCBT than clients. Conclusions. While cCBT is likely to be an effective and acceptable intervention for some people, there are barriers to its uptake that will substantially limit its impact if not addressed. These included investigating the outcome and attitudes of those who do not make it as far as cCBT trials and why so few finish a full course of cCBT.