There has been a huge expansion in the private health-care sector over the past two decades, particularly in South Asia, resulting in over 80% of patients seeking care from private health providers. Despite concerns about the quality and equity of private sector service provision, most government public health bodies recognize that the private sector reaches individuals that public institutions cannot cater to, thereby being important in moving closer to universal health coverage. Numerous initiatives have been launched and are being planned to involve private practitioners in effectively diagnosing, reporting and managing infectious diseases such as tuberculosis. However, there is a notable dearth of papers discussing which elements of private sector engagement strategies are more or less successful and the ethical issues that arise when engagement strategies are operationalized. This article brings together the authors' experiences of working on projects to engage private allopathic health providers in Pakistan, Bangladesh and India for improved tuberculosis control. Motivations of and strategies required to engage private allopathic heath providers, specifically doctors, diagnostic laboratories and pharmacies, and some of the ethical issues that arise when designing programmes for engagement are discussed.