Patients may be registered with the program through their physicians, who will be responsible for supervising the administration of treatment; following guidelines for saquinavir dose interruption, dose reduction, or discontinuation; and assessing patient progress throughout the duration of the study. Access to saquinavir will be determined by a lottery system; 60 percent of the program slots will be reserved for patients with CD4 counts of 50 or less and the remaining 40 percent of the slots will be devoted to patients with CD4 counts between 51 and 300.