OBJECTIVE: Electronic consultations (e-consults) are clinician-to-clinician communications that may obviate face-to-face specialist visits. E-consult programs have spread within the US and internationally despite limited data on outcomes. We conducted a systematic review of the recent peer-reviewed literature on the effect of e-consults on access, cost, quality, and patient and clinician experience and identified the gaps in existing research on these outcomes. MATERIALS AND METHODS: We searched 4 databases for empirical studies published between 1/1/2015 and 2/28/2019 that reported on one or more outcomes of interest. Two investigators reviewed titles and abstracts. One investigator abstracted information from each relevant article, and another confirmed the abstraction. We applied the GRADE criteria for the strength of evidence for each outcome. RESULTS: We found only modest empirical evidence for effectiveness of e-consults on important outcomes. Most studies are observational and within a single health care system, and comprehensive assessments are lacking. For those outcomes that have been reported, findings are generally positive, with mixed results for clinician experience. These findings reassure but also raise concern for publication bias. CONCLUSION: Despite stakeholder enthusiasm and encouraging results in the literature to date, more rigorous study designs applied across all outcomes are needed. Policy makers need to know what benefits may be expected in what contexts, so they can define appropriate measures of success and determine how to achieve them. Informatics Association 2019. This work is written by US Government employees and is in the public domain in the US.