The last few decades have seen increasing use of computer-based programmes to address illicit recreational drug use but knowledge about their effectiveness is limited. We conducted a systematic review to examine evidence on these programmes. Eight electronic databases were searched to identify primary research studies evaluating computer-based programmes to prevent or reduce use of illicit recreational drugs. From an initial 3413 extracted studies, 10 were identified for inclusion, covering a range of intervention types, target groups and settings. Universal drug prevention programmes were effective in reducing the frequency of recreational drug use in the mid-term (<12 months), but not immediately post intervention. Programmes targeting recreational drug users showed more inconsistent results but were generally effective in reducing use of drugs both immediately and in the mid-term. Computer-based programmes have the potential for use in addressing recreational drug use when targeted both universally and at illicit drug users, at least in the mid-term. However, longer term evaluations are needed to better understand the duration of effects. Given the benefits that computer-based programmes can have over traditional delivery methods, research is needed to better understand the value of human contact in health interventions and help inform whether, and how much, professional contact should be involved in computer-based programmes.