The present study evaluates the in vitro cellular immunity response in cases of suspected Acquired Immunodeficiency Syndrome (AIDS). The immunological features of 111 patients were correlated with those from eleven healthy controls. Patients were divided into three groups: RISK, LAS/ARC and AIDS, using CDC criteria. The AIDS showed leucopenia, lymphopenia, diminished number of T and B lymphocytes, normal number of thermostable E-rosette forming cells (TE), decreased helper-inducer T cell, elevated suppressor-cytotoxic T cell, reversed helper T cell/suppressor T cell ratio and depressed proliferative response using mitogens like phytohemagglutinin (PHA), concanavalin-A (Con-A), pokeweed mitogen (PWM) and purified protein derivative antigen (PPD). These findings confirm a severe deficiency in cellular immunity and permit to establish an immune cellular profile, characteristic of the AIDS patients.