There is no other field of medicine that has been through such dramatic developments as that of antiretroviral therapy . In September 1995 , the results of Eurpean-Australian DELTA study , and the American ACTG pointed out that two nucleoside analogues were more effective than monotherapy .This led to the belief , thatlonger survival was possible in HIV .Protease inhibitors (PIs ) came about in 1995 , and in June 1996 , the first non-nucleoside reverse transcriptase inhibitor (NNRTI ) neviparine arrived , and so did Nelfinavir which was a new PIs . This led to the start of HAART (Highly Active Anti-Retroviral Therapy .Antiretroviral drugs have been divided into a number of groups on the basis of the phase of the retrovirus life-cycle that the drug inhibits .1 Nucleoside nucleotide reverse transcriptase inhibitors (NRTI )inhibit reverse transcription by incorporating into the newly synthesized viral DNA and slowing its elongation . Apricitabine (AVX-754 )is a heterocyclic cytidine analog , which may enter the market in 2009 .Elvucitabine is currently in phase II trials . Stampidine is 100 times more potent than AZT and has potential role against HIV mutants 2 Non-nucleoside reverse transcriptase inhibitors (nNRTI ) inhibit reverse transcriptase directly by binding to the enzyme and not allowing its function . Efavirenz has been the agent that has been most successful , but is facing lot of viral resistance . Rilpivarine has a long half life of 40 hours .3 Protease inhibitors (PIs ) target viral architecture by inhibiting the activity of protease , an enzyme used by the virus to form new virons from the older protein framework . PL-100 is given as a prodrug and is active against multi PIs resistant strains . It has a long half life of 37 hours , and can act as a co-drug .4 Integrase inhibitors inhibit the enzyme integrase (integrates viral DNA into DNA of the infected cell . Raltegravir became the first to receive FDA approval in October 2007 . it is the most exciting of all anti HIV agents in the market . It acts against HIV-2 also . Elvitegasir has a potential as monotherapy .5 Entry inhibitors (or fusion inhibitors ) prevent the binding , fusion and entry of HIV-1 virus into the host cell . It acts via the gp 120 envelope protein to the CD 4 receptor . Maraviroc and enfuvirtide are marketed agents of this group .6 Maturation inhibitors- inhibit the last step in gag processing in which the viral capsid polyprotein is cleaved , thereby blocking the conversion of the polyprotein into the mature capsid protein (p24 .These virons are thus incomplete and thus uninfective . Two drugs in this group are under investigation , bevirimat ,`and Vivecontm .7 . Immunotherapy . IL-2 is a cytokine from the activated T – cells ,which induces proliferation in T , B , and NK cells . It causes an increase in CD 4 and CD 8 cells . It is useful in patients with poor immunological response to antiretroviral therapy to stimulate the immune system .G-CSF , GM CSF are used for treatment of prolonged neutropenia in patients with advanced HIV infection to reduce bacterial infection .Why is treatment of HIV difficult ?The retrovirus has an extremely…