We conducted a systematic review of research into callers making multiple calls to crisis helplines. Two databases were searched, identifying 561 articles from 1960 until 2012, of which 63 were relevant. Twenty-one articles from 19 separate studies presented empirical data about callers making multiple calls to crisis helplines. Of the 19 studies, three were intervention studies, five were surveys of callers and 11 were call record audits. Most studies were conducted in the USA and defined frequent callers as people making two or more calls. Frequent callers were more likely to be male and unmarried compared to other callers. There were no reported differences between frequent callers and other callers with regard to age, mental health conditions or suicidality. Three studies tested interventions designed to better manage frequent callers. These studies, even though small, reported reductions in the number of calls made by frequent callers. Suggested techniques for responding to frequent callers included: limiting the number and duration of calls allowed, assigning a specific counsellor, implementing face to face contact, the service initiating contact with the caller instead of waiting for callers to contact the service, providing short term anxiety and depression treatment programmes by telephone, and creating a specific management plan for each frequent caller. Future work requires robust study design methods using larger sample sizes and validated measurements.