There are not enough relevant data about infectious diseases from children living in orphanages. Mostly, information come from children who were adopted to western developed countries, and they yearly count for 75 000. Very often, orphans are suffering from malnutrition and excessive number of infectious diseases such as respiratory tract infections, intestinal parasites, HIV, opportunistic infections and tuberculosis. Cambodia belongs to one of the most HIV-affected countries in South-East Asia region. Prevalence of HIV has tendency to decrease as in 2007 it was 0,8%. St. Elizabeth University has been running tropical program for HIV positive children in Phnom Penh and Sihanouquille in Cambodia since 2003. One hundred and two children (n=102) treated with HAART were included in the study. During 6 years we have observed different spectrum of infectious diseases in orphans. The most prevalent complication was pneumonia in 65% of children, followed by pyodermia in 64%, tuberculosis in 48%, Otitis media chronica in 38%, oropharyngeal candidiasis in 34%, parotitis recurrens in 24%, vasting syndrome in 23%, herpes zoster in 23%, persistent diarrhea in 10%, hepatitis B in 6%. Mortality was 2,99% in this period. Due to several episodes of opportunistic infections, HIV infected children received multiple courses of antimicrobial therapy, most often for treatment of (i) respiratory tract infections (cephalosporins, aminopenicillins, macrolides), (ii) candidiasis (fluconazole) and (iii) Herpes infections (acyclovir, valacyclovir). Nose and throat swabs were taken every three months. At the start of HAART, all isolates of Enterobacter spp. and Klebsiela spp. were resistant to cefotaxim. Interestingly, after three years of treatment with HAART, neither Enterobacter spp. nor Klebsiela spp. isolates were resistant to cefotaxim at all. In conclusion, we found out, that, reconstitution of immune status and increase of CD4 T-cells level as a result of HAART was associated with decreased colonization with cefotaxim-resistant Enterobacter sp. and Klebsiela spp. isolates in HIV-infected children.