3'-Azido-3'-deoxythymidine (AZT, Zidovudine) has been effectively used for HIV infection treatment. It inhibits virus reproduction through viral reverse transcriptase inhibition. However, the side effects of this anti-retroviral drug might be cumulative, particularly in its effects on the patients' DNA. As a nucleoside analogue, AZT might incorporate into hosts' DNA, and then form DNA adducts. This may result in potential long-term risks of mutagenesis in AIDS patients who received therapy. In this feasibility study, a (32)P-post-labeling thin-layer chromatography (TLC) assay is successfully used to measure AZT-DNA analogue and adducts formed in peripheral blood leukocytes of AZT treated patients. There are DNA analogue/adducts measured in all four AZT treated patients' DNA specimens. This assay is reliable with the significant coefficient of correlation in both intra-assay (r = 0.8761, P = 0.0001) and inter-assay (r = 0.8761, P = 0.0001).