In community settings, relatives often provide care to their older family members, which is sometimes perceived as a high burden, overwhelming and stressful, contributing to an increased risk of elder abuse. In most countries, relatives have no legal obligation to provide care when family members are admitted to nursing homes; nevertheless, studies have shown that relatives continue to provide emotional, instrumental, and personal care after admission, often related to the understaffing and high workload of nursing staff. Despite the growing interest in elder abuse in nursing homes, most studies have concentrated on the abuse perpetrated by nursing staff or co-residents, but few studies have explored the abuse that relatives may perpetrate. This study was a cross-sectional survey of 3,693 nursing staff members recruited from 100 nursing homes in Norway, to examine the extent of relative-to-resident abuse in Norwegian nursing homes, as observed by nursing staff. The findings indicate that 45.6% of the nursing staff had observed one or more episodes of relative-to-resident abuse during the past year. Among the subtypes of abuse, 44.8% of the nursing staff had observed psychological abuse, 8.4% had observed physical abuse, 2.7% had observed financial/material abuse, and 0.7% had observed sexual abuse at least once during the past year. This is the first large study exploring the extent of relative-to-resident abuse in nursing homes, which is a phenomenon that is significantly less addressed than abuse committed by staff and co-residents. The findings in our study illustrate that abuse committed by relatives needs more awareness and attention to improve the well-being of nursing home residents. Further research is recommended to enhance our understanding of such abuse and should include other approaches measuring the proportion of relative-to-resident abuse, as relying solely on staff observations is insufficient for determining the prevalence in this case. Future studies should also examine the cumulative impact of victimization in nursing homes and should include an analysis of how cases of abuse are reported and handled.