Objective: The objective of the review was to synthesize research studies that reported on the experiences and needs of families with a relative in an adult intensive care unit. Introduction: Having a relative in an intensive care unit has been reported to be a time of turmoil, stress, and disruption to the lives of family members. Primary research studies suggest such a crisis or even a planned intensive care unit admission can have not only emotional, physical, and psychological impact, but can also affect family member roles and function. A deeper understanding of the overall experience may assist intensive care unit staff to address specific family needs. Inclusion criteria: This review included qualitative studies of any design that described and explored the experiences and needs of family members with a relative admitted to an adult intensive care unit. Methods: The methods for the review followed the JBI meta-aggregation approach for synthesizing qualitative data. MEDLINE (EBSCO), CINAHL (EBSCO), PsycINFO (EBSCO), Embase (Embase.com) and Web of Science Core Collection (Clarivate Analytics) databases were searched for published studies. ProQuest Dissertations and Theses database (Ovid) was searched for unpublished studies. Studies published from 2010 to November 2019 in the English language were selected for possible inclusion in the review. Results: From 7208 citations, 20 studies were agreed upon for inclusion in the review. From these studies, 112 findings were extracted and synthesized into 12 categories. Four synthesized findings were compiled by aggregating the categories. Broadly, these synthesized findings related to: psychosocial health, proximity, information needs, and the intensive care unit environment. Conclusions: Being a relative of a patient in an intensive care unit is a complex, emotional, and individual experience that can have physical, psychological, and emotional impact. The synthesized findings from this review can be used to support family-centered care practices in adult intensive care units, particularly in regard to information provision, visiting practices, and supportive care. Systematic review registration number: PROSPERO CRD42016053300