OBJECTIVE:To establish a method for the uncertainty evaluation of determining content of Lamivudine tablets by HPLC. METHODS:HPLC was established to determine the mathematical model of Lamivudine tablets contents,analyze the uncer-tainty sources in detail and evaluate each uncertainty components and combined uncertainty to obtain the expanded uncertainty. RE-SULTS:Uncertainty of Lamivudine tablets contents determined by HPLC was mainly from reference purity,weighing standard and glassware tolerance. Standard uncertainty was 0.21% and expanded uncertainty was 0.42%. The range of content determination was (99.76 ± 0.42)%,k=2. CONCLUSIONS:The method is suitable for uncertainty evaluation of Lamivudine tablets by HPLC,and provides reference for the quality control in laboratory and objective evaluation of Lamivudine tablets.