Objectives: To evaluate how eight major medical comorbidities of dementia (arthritis, cancer, diabetes, heart disease, hypertension, lung disease, osteoporosis, and stroke) are associated with caregivers' perceptions of emotional caregiving difficulties and caregiving gains (ie, benefits or rewards from the care role).; Design: Nationally representative cross-sectional surveys of community-dwelling persons living with dementia (PLWDs) and their co-resident family caregivers in the United States.; Setting: The 2011 National Health and Aging Trends Study and National Study of Caregiving.; Participants: Total of 356 co-resident family caregivers of community-dwelling PLWDs.; Measurements: Caregivers' sociodemographic and health characteristics, caregiving stressors, emotional caregiving difficulties, caregiving gains, and chronic health conditions of PLWDs.; Results: Caregivers most commonly cared for a PLWD with arthritis (65.5%), followed by hypertension (64.9%), diabetes (30.1%), stroke (28.8%), osteoporosis (27.1%), heart disease (23.3%), cancer (21.5%), and lung disease (17.2%). Logistic regressions revealed that caregivers were 2.63 and 2.32 times more likely to report higher than median emotional caregiving difficulties when PLWDs had diagnoses of diabetes and osteoporosis, respectively, controlling for caregiver sex, relationship to the PLWD (spouse vs non-spouse), educational attainment, self-rated health, and assistance with activities of daily living and medical care activities. Caregivers were also 2.10 times more likely to report lower than median caregiving gains when PLWDs had a diagnosis of osteoporosis.; Conclusion: Comorbid health conditions among PLWDs have distinct implications for caregiving outcomes. Clinical care and interventions to improve the well-being of both care dyad members should support caregivers in managing medical comorbidities of dementia.