Over the last decade, health informatics has risen to prominence in New Zealand's health management landscape. The importance of better health-related data management and generating insights from the system is growing in popularity. This research aims to determine the major themes of health informatics in New Zealand. The research uses a systematic literature review to identify the major themes. With the systematic literature review, the research found that health informatics is focused in the following themes: conceptualisation of health informatics, big data analytics (BDA) in health informatics, types of health information systems, history of health informatics, and teaching nursing informatics. The themes are interrelated to enhance the better provision of services and establish answers to challenges that threaten existing services. Based on the research findings, the discussion is presented to guide health informatics researchers, and will help them to identify the research themes that can be investigated further. The interrelationship between these themes is based on the idea that they concentrate on devices, methods, and interventions needed to promote the attainment of big data analytics in health informatics and its use in medical and health decision-making. This study might also guide the development of health informatics policies in the nation. Based on the faster development of health informatics, the interaction of these themes offers opportunities for informatics specialists to enhance the practices and services in the medical field.