Introduction: Enhancing quality of health care delivered in public health facilities in developing countries is a key prerequisite in increase utilization and sustainability of the health care service in the population. Objectives: The objective of this study was to explore health care provider’s perception and client’s level of satisfaction on the quality of health care delivered at OPD in Mwananyamala hospital, Dar es Salaam Tanzania. Methods: A descriptive cross-sectional study, using both qualitative and quantitative approaches. Donabedian model was used to explore provider’s perception and client’s level of satisfaction on quality of care in Mwananyamala hospital from April to May 2012. Purposive sampling was used to select 20 to 30 health care providers working at the OPD and systematic sampling was used to select 422 clients attending OPD during the study period. The male: female ratio was 1:1 among 18 year olds or above. 10 in-depth interviews, 4 with hospital key informants and 6with head of unit at the OPD and 2 focus group discussions with 17 participants, health care providers working at the OPD, were conducted to collect information on provider’s perception on the quality of health care. A pre-tested SERVQUAL questionnaire was used to collect data from 422 clients at the OPD. Quantitative data was processed and analyzed by using STATA software version 12.1 and qualitative data was analyzed by thematic analysis. Results: HCPs perceive the quality of care to be low due to frequent unavailability of working equipment, low motivation at work, inadequate staff and poor infrastructure at the hospital. But they praise the hospital management for considering them in on job training. Clients mean gap score was -2.88 that indicates overall dissatisfaction with the quality of care among majority clients. The level of dissatisfaction was higher in responsiveness with mean gap of -0.722, followed by empathy with a mean gap of -0.554, tangible mean gap score -0.515, reliability mean gap score -0.494 and lastly assurance with the mean gap score of -0.466. vii Conclusion: The findings indicate areas for improvement as staff inadequacy, low motivation at work, training, availability of working equipment, availability of drugs, confidentiality, patient-provider relationship, waiting time and hospital cleanliness. The Ministry of Health and Social Welfare and Kinondoni municipal management have to work on these areas in order to improve the quality of health care in the OPD. Improved quality of care in the OPD will improve health seeking behavior and utilization of health services in public hospitals. It will also reduce bypass of public hospital facilities.