Comparing the Effectiveness Between Ritonavir Boosted Atazanavir and Efavirenz for the First HIV Treatment

Inclusion Criteria: * serological diagnosis of HIV infection * male aged over 20 years old * CD4 at enrollment between 100 to 300 * body weight over 40kg * enable to obtain the written informed consent Exclusion Criteria: * Patients who are considered unable to complete 48 weeks of study by their physician. * Patients who have gastrointestinal symptom which may interfere the absorption of antiretrovirals, or have swallowing problems. * Patients who have the history of hypersensitivity with lamivudine. * Hepatitis B carrier. * Blood test results within 4 weeks prior to the randomization; hemoglobin less than 9g/dl, platelet less than 50,000/mm3, neutrophils less than 1000/mm3, serum total bilirubin more than 2.0mg/dl, GOT/GPT/LDH more than two times of upper normal limit, serum creatinine more than 1.2mg/dl. * Patients who have had radiation or chemotherapy within 4 weeks prior to the randomization or will have the treatment during the study . * Patients who have had immunomodulating agent such as systemic use of corticosteroid or interferon within 4 weeks prior to the randomization. Inhaled corticosteroid is the exception. * Patients who have diabetes, congestive heart failure, cardiomyopathy, or other serious medical condition. * Patients with AIDS defining illness. * Patients with known resistant strains to efavirenz, atazanavir, ritonavir, lamivudine and abacavir prior to the study. * Patients with acute retroviral syndrome. * Patients with psychiatric disorder. * Patients whose physician consider the study enrollment inappropriate.