We report the case of a 54-year old man with decompensated alcoholic liver cirrhosis and HIV infection who underwent liver transplantation (LT). Due to relatively well preserved cellular immunity until 2003, no antiretroviral therapy (HAART) needed to be instituted. However, deterioration of his clinical state indicated LT. At that time, the viral load was of 4.84 Log and the CD4 count was more than 250 cells/mm3. The posttransplant course was complicated by several infection episodes and one episode of acute cellular rejection grade 2. HAART consisted of Lamivudine, Stavudine, Lopinavir and Ritonavir. One week after beginning of HAART, tacrolimus was discontinued during 18 days due Ritonavir interaction. CD3/CD4 T-helper lymphocyte count showed a significant decrease immediately after LT which rapidly recovered after initiation of HAART. The patient was discharged on the 8th postoperative week in good conditions. This report encourages the institution of HAART once the liver graft regains normal function. Drug interactions between Ritonavir and Tacrolimus should be anticipated. A study protocol to manage these patients within a multidisciplinary team including also specialists in infectious diseases and virologists is mandatory.