Background: HIV is isolated in 1983, human immunodeficiency Virus (HIV), the agent thatrncauses acquired immune deficiency syndrome (AIDS), is classified as members of thernlentivirus subfamily of retroviruses. There are two main types of HIV: HIV type 1(HIV-1): thernmost prevalent throughout the world. HIV type 2 (HIV-2) is prevalent in West Africa. Theyrnboth cause ADIS and the routes of transmission are the same. However, HIV-2 causes AIDSrnmuch more slowly than HIV-1. Although HAART is known to profoundly suppress viralrnreplication, it increases CD4 cell count and delays disease progression and death; patientsrnon Highly Active Antiretroviral Therapy (HAART) commonly suffer from side effects of therndrug. Each antiretroviral drug is associated with specific adverse effects. Several studies inrndeveloped countries have shown that AZT alone and AZT based HAART regimen isrnassociated with significant reduction of hemoglobin (Hb) level and neutrophil number. Thernimpact of its immunological recovery rate / including at what time to start on Treatment isrnnot well known in Ethiopian context. Hence this research was conducted to determine itsrnimmunological responses at different interval and at the start.rnObjective: The aim of this retrospective cohort study was to describe immunological responsernamong HIV-infected individuals receiving highly active antiretroviral therapy (HAART) withrnlong-term follow-up.rnMethod: A Cohort retrospective study design was conducted to assess immunological (thernCDrn4rn+rnrecovery) among HIV-infected individuals receiving highly active antiretroviral therapyrn(HAART) with long-term follow-up. Antiretroviral-naive patients with symptomatic HIVrndisease at baseline (before ART) and after 6 and 9 and 12 months of ART will be collectedrnfrom records and after start ART in Zewditu Hospital, Addis Ababa, Ethiopia.rnResult: A total of 887 HIV positive patients in this research; Out of these 472 (53.2%) werernfemale and 415 (46.8%) male patients. The ratio of male to females was almost 1:2. None ofrnthem have any opportunistic infection during the time of follow up. The mean age of the studyrngroup was 36.76 (17-76). The mean baseline CD4 was 81.40; the mean CD4 count at the 6rn,rn9rnthrnand 12rnthrnmonth was 191.65, 284 and 331 respectively. There was a good immunernrecovery at the 6rnthrnmonth of therapy from the baseline mean CDrn4rn+rnT cell count of 81 cells /ïlrnto 191.65 cells /ïl, which was statically highly significant (p200 than when they start ART at CD4 count >200rnCD4 cell. Therefore, interventions need to be designed to promote early HIV testing andrnearly enrollment of HIV infected individuals into ART services. ART has considerablyrnimproved the immune recovery. We strongly recommend underline the need of anti-retroviralrntherapy in HIV infected patients for immune reconstitution should be started as early asrnpossible. The differential recovery rate between those with base line CD4+ T cell countrnbelow 50cells/ïl and above 500cells/ïl needs further investigation.