Background and Aim: Discussing cost during medical encounters may decrease the financial impact of medical care on patients and align their treatment plans with their financial capacities. We aimed to examine which interventions exist and quantify their effectiveness to support cost conversations. Methods: Several databases were queried (Embase; Ovid MEDLINE(R); Epub Ahead of Print, In-Process & Other Non-Indexed Citations and Daily; the Cochrane databases; and Scopus) from their inception until January 31, 2020 using terms such as “clinician*”, “patient*”, “cost*”, and “conversation*”. Eligibility assessment, data extraction and risk of bias assessment were performed independently and in duplicate. We extracted study setting, design, intervention characteristics and outcomes related to patients, clinicians and quality metrics. Results: We identified four studies (1327 patients) meeting our inclusion criteria. All studies were non-randomised and conducted in the United States. Three were performed in a primary care setting and the fourth in an oncology. Two studies used decision aids that included cost information; one used a training session for health care staff about cost conversations, and the other directly delivered information regarding cost conversations to patients. All interventions increased cost-conversation frequency. There was no effect on out-of-pocket costs, satisfaction, medication adherence or understanding of costs of care. Conclusion: The body of evidence is small and comprised of studies at high risk of bias. However, an increase in the frequency of cost conversations is consistent. Studies with higher quality are needed to ascertain the effects of these interventions on the acceptability, frequency and quality of cost conversations.