Introduction: Healthcare has greatly changed due to issues such as rapidly aging population with decreasing birthrate, also patients’,preference of receiving care at home. Home health care nurses need to assess the needs and limitations of the patient and family for holistic approach aimed at empowering patients, families, and caregivers to achieve their highest levels of physical, functional, spiritual, and psychosocial health. Therefore home health care nurses should have the skills to assess in Home health care. The aim of this study was explain the nurse's competency in "assessment" the provision of home health care. Methods: The present study is a qualitative conventional content analysis that was conducted in home health care centers in Tehran in 2020. With purposive sampling to data saturation, 15 home health care nurses were selected and data were collected using semi-structured individual and in-depth interviews, and then, the analysis was performed by the method of conventional content analysis in accordance with Zhang's (2009) approach. Results: Content analysis of the data led to the extraction of the 176 cods, 12 subcategories, 3 categories and one theme of care comprehensive assessment in home health care that included categories: comprehensive assessment of the patient, assessment of the family and assessment of the care environment. Conclusions: The findings of the study provided one of the HHC nurses' competencies namely care comprehensive assessment in home health care, which contributes to practice HHC nurses can assess their professional activity and think over the aspects to be completed and refined, That the result is to improve the quality of care and increase patient, family and nurse satisfaction. Also, there can be a basis for educational curriculum development.