Health literacy and patient web portals.

•There is limited evidence about the association between health literacy and use of patient web portals in patients with chronic illnesses.•Qualitative studies and studies with a cross-sectional, cohort, or pre-/post-test study design have shown that persons with limited health literacy are less likely to use patient web portals, although not all studies have found an association.•Several opportunities exist to improve the usability and acceptability of web portals for patients with limited health literacy including enhancements in the design of the portals, patient and provider education and training, and engagement of proxies such as caregivers and close family members.•Studies are needed of use of web portals and adherence with prescribed medications and other forms of treatment by patients with varying levels of health literacy.