Background: People with dementia often have a poor quality of life. Therefore, methods that can improve their life situation must be identified. One promising method is dog-assisted intervention. Aim: This study aimed to investigate the effects of dog-assisted intervention on quality of life in nursing home residents with dementia. Materials and methods: A one-group, pretest post-test study design was used. Quality of life was measured using the QUALID in 59 nursing home residents prior to and after a dog-assisted intervention. Non-parametric tests were used to analyze the data, and effect sizes were calculated. Results: The participants' total scores improved significantly between baseline and post-test 1 (p ¼ < 0.001) and worsened significantly at post-test 2 (p ¼ 0.025). The largest effect size was found for the item 'Verbalization suggests discomfort' (p ¼ 0.001). Conclusion:The results indicate that dog-assisted interventions can have positive effects on quality of life in nursing home residents with moderate to severe dementia. Significance: The results contribute to a growing knowledge base about non-pharmacological methods that can be used in dementia care. Occupational therapists should consider dogassisted interventions when planning activities that can reduce the illness burden and improve the quality of life for people with dementia.