Purpose: In Tanzania, women are diagnosed at advanced breast cancer stages. The reasons for this are multifactorial and have not been systematically investigated in the Kilimanjaro Region. This study aimed to identify reasons for advanced stage breast cancer at time of diagnosis. Methods: Four focus group discussions and 8 semi- structured in-depth interviews were conducted among health care providers (HCP) and traditional healers from five health care facilities (1 regional and 2 district hospitals) and two urban and rural communities in Kilimanjaro, Tanzania. Thematic coding via grounded theory technique was done by two independent reviewers. Results: Twenty HCP (10 doctors and 10 nurses) and 8 traditional healers participated in the study. The average ages for doctors were 38, nurses 33, and traditional healers 50. Among HCP, the most common reasons for advanced stage breast cancer at time of diagnosis were patients initially seeking care from traditional healers, and patient distrust of conventional medicine. Among traditional healers, the most common reasons were: delayed initiation of biomedical treatment due to long turnaround of pathology results, inability to pay for diagnostic workup and treatment, and transportation issues. Both groups stated lack of patient breast cancer knowledge. Conclusions: There was agreement that lack of adequate breast cancer knowledge and awareness as a very common reason for advanced disease presentation among HCP and traditional healers. Community health education must be designed to adopt socio-cultural and religious doctrines to alleviate the misconceptions and knowledge gap. Health system interventions are also needed to facilitate access to timely, affordable, and quality breast cancer diagnosis and treatment Citation Format: Elizabeth F. Msoka, Lily Gutnik, Agnes M. Cyril, Brenda C. Kitali, Vivian F. Saria, Jackline C. Kwayu, Adellaida A. Kavishe, Perry C. Msoka, Ayesiga Herman, Furaha Serventi, Gilleard G. Masenga, Oluwadamilola Fayanju, Laura Fish, Blandina Th. Mmbaga. Health Care Providers and Traditional Healers Perspectives on Late Diagnosis of Breast Cancer in Tanzania: A Qualitative Study [abstract]. In: Proceedings of the 9th Annual Symposium on Global Cancer Research; Global Cancer Research and Control: Looking Back and Charting a Path Forward; 2021 Mar 10-11. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2021;30(7 Suppl):Abstract nr 77.