The number of MSM living with a diagnosis of HIV increases by approximately 20,000 each year (new infections [2] minus deaths [1]), which would produce an absolute increase in prevalence of less than one-half of one percent of the MSM population over three years. If the size of the MSM population is increasing, as is the rest of the U.S. population [18], the expected increase would be further reduced. One important difference between the population of HIV-infected MSM and NHBS is the age distribution; NHBS captures a younger sample of MSM.