Acquired immunodeficiency syndrome (AIDS) is one of the most serious public health problems in the world, which greatly affects the socio-economic growth. Mathematical models can serve as tools for understanding the epidemiology of human immunodeficiency virus (HIV) and AIDS. In this paper, we consider a mathematical model having three compartments. Uninfected and infected states are proposed and analysed. It is found that the uninfected state is locally stable when the reproduction number R0 < 1 and the infected state is locally stable when R0 ≥ 1 and globally stable when R0 > 1. The model is analysed with and without delay. Numerical simulations are carried out to illustrate the results.