Although many countries are now collecting useful, high-quality HIV surveillance data, more efforts are put into the collection of data than into ensuring it is deployed effectively. The Canada-Pakistan HIV/AIDS surveillance project has strengthened and expanded the existing national AIDS control programme surveillance system in Pakistan through a comprehensive estimate of the size and location of some of the most at-risk populations (sex workers and injection drug users) and annual assessments of their sociodemographic characteristics, behaviours and HIV prevalence. The country now uses second generation surveillance data at a broad level to lobby for policy change, mobilize resources, improve programming and measure the success of prevention through an integrated national effort. This article aims to share the experiences and lessons learnt in the development of a second generation surveillance system for HIV/AIDS in Pakistan.