A prospective study of 149 human immunodeficiency virus type 1 (HIV-1) seroconverters was conducted to describe trends and correlates of HIV-1 load after seroconversion and over time. HIV-1 load was quantified from frozen sera by reverse transcriptase-polymerase chain reaction. High early virus load was associated with lower CD4 cell counts and male sex but not with age at seroconversion or injection drug use. Early virus load predicted progression to clinical AIDS and AIDS/<200 CD4 cells/microL. Virus load exhibited a decline of 52% by 18 months after seroconversion then increased 23% annually (95% confidence interval, 13%-33%). Men and those developing AIDS during follow-up had higher virus loads over the course of disease. Persons who developed AIDS had a steeper virus load slope than those who were AIDS-free (P=.01). In long-term follow-up, virus load exhibited a gradual and sustained increase over time. Virus load and annual increase are strong predictors of disease progression.