Cumulative rates of loss to follow-up, estimated by the Kaplan-Meier method, are plotted for Groups I, IIa, and IIb using information available through of March 31, 1996. The cumulative loss-to-follow-up rate for all Group II children (not shown) is higher than for Groups IIa or IIb because the rates for Groups IIa and IIb exclude HIV-indeterminate children who are lost to follow-up before their HIV status can be determined. Loss-to-follow-up rates for all Group II children combined, including HIV indeterminates, are 26.9%, and 38.3% at 24 and 36 months, respectively.