Background: resident-to-resident aggression (RRA) is an understudied form of elder abuse in nursing homes.Objective: the purpose of this systematic review was to examine the published research on the frequency, nature, contributing factors and outcomes of RRA in nursing homes.Methods: in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Statement, this review examined all original, peer-reviewed research published in English, French, German, Italian or Spanish between 1st January 1949 and 31st December 2013 describing incidents of RRA in nursing homes. The following information was extracted for analysis: study and population characteristics; main findings (including prevalence, predisposing factors, triggers, nature of incidents, outcomes and interventions).Results: eighteen studies were identified, 12 quantitative and 6 qualitative. The frequency of RRA ranged from 1 to 122 incidents, with insufficient information across the studies to calculate prevalence. RRA commonly occurred between exhibitors with higher levels of cognitive awareness and physical functionality and a history of aggressive behaviours, and female targets who were cognitively impaired with a history of behavioural issues including wandering. RRA most commonly took place in the afternoon in communal settings, was often triggered by communication issues and invasion of space, or was unprovoked. Limited information exists on organisational factors contributing to RRA and the outcomes for targets of aggression.Conclusions: we must continue to grow our knowledge base on the nature and circumstances of RRA to prevent harm to an increasing vulnerable population of nursing home residents and ensure a safe working environment for staff.