The Union is probably most widely known for the field research it conducted in the 1980s that led to the development of the directly observed treatment, short course strategy for TB control that became branded by WHO as DOTS. This DOTS strategy, which remains central to the current Stop TB Strategy, has been used to treat more than 37 million TB patients since 1995.

Research aimed at finding solutions to the health challenges of the poor has always been an integral part of The Union's work, whether the issue be redesigning a treatment regimen or finding a more effective way to record data. Research activities are coordinated through the Department of Research, and each proposed project is reviewed and approved by the Ethics Advisory Committee. These oversight activities are a reflection of the high value placed on the quality of the research conducted by and in partnership with The Union.

Operational research is an excellent way for public health programmes to identify, study and solve local problems. The Union fosters this type of capacity building not only through the research projects in which it is involved, but also through its other activities, such as technical assistance and training.

The Centre for Operational Research both conducts research and offers variety of training opportunities and an OR fellows programme. Emphasis is placed not only on doing the research, but reporting and publishing it, so that others can benefit.

The Clinical Trials Unit both conducts trials and has helped build local capacity for this type of research by qualifying centres around the world to participate in Union trials.

Union staff and consultants are highly active in their fields and the results of their work are regularly published in journals such as Clinical Infectious Diseases, European Respiratory Journal, Journal of the American Medical Association, Lancet, Thorax and Tropical Doctor.