With the recognition of different population behavior and relevance of socio-cultural factors in health, health services and public health program contexts, qualitative research is increasingly being used in health research, including clinical trials. Qualitative research follows an inductive framework to explore and gain an in-depth understanding of the phenomena, especially why and how aspects, through techniques including interviews, focus groups and observations. It analyzes the textual data collected following one of the common analysis approaches: grounded theory, phenomenology, ethnography or participatory action research. Despite the divergence in principles, mixed methods research designs systematically combine the quantitative and qualitative methods for a comprehensive understanding on the issue. The commonly used mixed methods designs variably combine the purpose, priority, sequence, embedding and data integration. Mixed methods analysis requires strategic synthesis of the results to gain comprehensive knowledge for appropriate clinical or public health action.