Nurses, the mainstay of the healthcare system, occupy a significant position at all tiers of health care. Inadequate number of nursing staff affects the quality of nursing care and also elevate the burden of workload on existing staff. This study aimed to assess factors influencing nurses' job satisfaction and retention in a public sector tertiary care hospital in Pakistan. An exploratory qualitative study was used to explore nurses' perception of job satisfaction at work. Study was carried out during July to September, 2016 at public sector tertiary care hospital of Pakistan using purposive sampling technique. Study participants were nurses, providing direct patient care and head nurses in 10 different units of hospital. Focus Group Discussions were conducted with staff nurses from eleven different clinical units. In-depth interviews with head nurses and Human Resource/Administration personnel. Human Resource policy related documents were also reviewed. Lack of career growth prospects and in-service education and trainings, professional discrimination between physicians and nurses, high work load and shortage of staff were the important factors indicated by participants for job dissatisfaction. Nurses also expect recognition for their work and respect from their co-workers. Job satisfaction among nurses can potentially increase quality of nursing care. The study highlighted the need to implement fair and equitable policies for nursing workforce at hospital. Simple measures for better management practices could significantly improve the working conditions and hence retention of nurses in the longer run.