This paper describes a program to increase patients' treatment literacy regarding viral load (VL) monitoring through patient education materials and a counseling protocol, implemented by peer counselors, in order to reinforce adherence to first-line treatment. VL monitoring and second-line antiretroviral treatment were introduced into an established first-line treatment program in a rural district hospital in Thailand. All patients (171 adults and 14 children) taking antiretroviral treatment for more than 6 months participated and those with detectable VL were targeted for additional adherence support. The main outcome measure recorded was the number of detectable results becoming undetectable after counseling. Four adults and one child had a persistently high VL and switched to second-line treatment. Of 51 adults (30%) with an initial low detectable VL, 47/51 identified likely explanations, usually linked with poor adherence. Following counseling, VL became undetectable in 45/51 cases and some patients could resolve long-standing psychosocial problems. We conclude that HIV-1 VL monitoring together with targeted counseling for patients with detectable VL can promote adherence to treatment, providing an opportunity to delay onset of HIV-1 resistance. When implemented with a patient-centered approach, it can be a very useful tool for psychosocial support.