Drawing on data from existing cohorts and from publically available population databases, the British Columbia Centre for Excellence in HIV/AIDS has built projection models to estimate HIV risk and health profiles of HIV-positive and -negative gay, bisexual and other men who have sex with men (MSM). These population models have drawn on demographic, epidemiologic and mathematical methods. Population Modelling aims to derive best possible estimates of HIV incidence and clinical outcomes in local, provincial and global settings.