While tobacco helplines (quitlines) are thought to be effective, helplines which treat other substance use do not have an established evidence base. A review was conducted of the literature on illicit drug or alcohol (IDA) helplines. The literature search was conducted in five databases. Studies prior to 2014 were included if published in English, and involved the use of a telephone counselling helpline for the treatment of illicit drug or alcohol use. Review papers, opinion pieces, letters or editorials, case studies, published abstracts and posters were excluded. Initial searching identified 2178 articles and after removing duplicates and those meeting the exclusion criteria, there were 36 publications for review. A total of 29 articles provided descriptive information about 19 different IDA helplines which operated in the US (42%), Europe (21%), Australia (21%), Asia (11%) and Canada (5%). These services reported monthly call rates from 3.7 to over 23,000 calls per month. A total of nine articles provided evaluative information on eight different IDA helplines: four articles included a comparison of treatment outcomes against a control group and five articles included information on treatment satisfaction or service utilisation. Together they provide some evidence that these services are effective. Although there was little consistency in the measures used between articles which assessed helpline satisfaction, all but one reported high satisfaction. Although the evidence is mainly supportive of IDA helplines, further work is required to compare treatment outcomes in randomized groups.