Background: Training of mid-level providers is a task sharing strategy that has gained popularity in the recent past for addressing critical shortage of health workforce. In Tanzania, training of mid-level providers has existed for over five decades, however, concerns are upon the quality of the mid-level cadres amidst the growing number of medical universities. This study sought to explore the challenges facing the training of the Assistant Medical Offices in Tanzania.Methods: An exploratory qualitative case study was carried out in four regions to include one rural district in each of the selected regions and two AMOs Training Colleges in Tanzania. A semi-structured interview guide was used to interview 29 Key informants from the district hospitals, district management, regional management, AMOs training college and one retired AMO. In addition, four focus group discussions were conducted with 35 AMO trainees.Results: Training of AMOs in Tanzania faces many challenges. The challenges include; use of outdated and static curriculum, inadequate tutors (lack of teaching skills and experience of teaching adults), Inadequate teaching infrastructure in existence of many other trainees to include interns, and limited or lack of scholarships and sponsorship for the AMO trainees. Conclusions: The findings of this study underscore that the challenges facing AMO training have the potentials to negatively impact the quality of care rendered by this cadre. Holistic approach is needed in addressing these challenges. The solutions should focus on reviewing the curriculum, deploying qualified tutors and improving the competencies of the available tutors through continued medical education programmes. Furthermore, the government in collaboration with other stakeholders should work together to address the challenges on teaching infrastructure and financial support to this cadre that has continued to be the backbone of the primary health care in Tanzania. Long term solution should consider to deploy the medical officers at the primary facilities and phase out the AMOs. Finally, challenges facing mid-level providers in Tanzania and similar settings are similar, thus these findings can be used as a starting pointing in addressing them.