Background:Cancer caregiving is a distressing experience and loss of a loved one can lead to intense grief and other adverse effects. However, the prevalence of grief disorders among families associated with cancer-related deaths remains unknown.Aim:This study aimed to determine the prevalence of grief disorders among families of patients with cancer to better inform clinicians, researchers, and policymakers.Design:Meta-analysis, PROSPERO number CRD42020209392.Data sources:The databases of CINAHL, Embase, MEDLINE, PubMed, Scopus, PsycINFO, and Web of Science were comprehensively searched with no language restrictions. The quality of included studies was assessed with Hoy’s criteria.Results:Among the 3046 records screened, 19 studies were eligible for meta-analysis, with a total of 14,971 participants. The pooled prevalence rate of grief disorders was estimated at 14.2% (95% CI, 11.7%–16.7%), ranging from 7% to 39%. The prevalence was higher in females (10%; 95% CI, 8.2%–12.1%), those who are religious (9.55%; 95% CI, 8.97%–10.16%), spouses of the deceased (7.78%; 95% CI, 6.08%–9.69%), and families of patients with neurological cancers (6.4%; 95% CI, 0.10%–19.9%). Educational levels, study locations, diagnosis tools, time post-after loss, and study methods seemed not to affect the prevalence of grief disorders in families of patients with cancer.Conclusions:As the prevalence of grief disorders in cancer-related bereavement is substantial, therefore, support including palliative care is important to reduce the burden of caregiving. In addition, future studies are needed to identify and explore effective strategies that can help reduce the burden caused by grief disorders after the death of the patient.