Treatment guidelines have used surrogate(laboratory-based) data from prospective studies of the natural history of the disease to guide the time to starttherapy. These data have been added to the current knowledgeof the effectiveness and tolerability of current combinationtreatments and the willingness of an infectedperson to start therapy. Most patients will start therapyonce their CD4 count is 350 x 106/L or below, but nationalguidelines vary and so do the motivation and willingnessof individual patients.A significant proportion of patients present and arediagnosed in latent disease when symptomatic and haveCD4 counts of