Abstract: AIM: The experiment was carried out in mice to study the tissue distribution characteristics of harmine (HAR) intravenous emulsion and quantitatively evaluate it as targeting drug delivery system. METHODS: Harmine was labelled with 3H as a tracer isotope. The distribution of ³H to the various organs and blood of mice, following its iv administration(1.85×10⁷ Bq.kg^-1) as an emulsion, a solution and liposome, was determined by liquid scintillation counting technique. The total radioactivity-time curves in important tissues were obtained. The weighted-average overall drug targeting efficiency (Te^*) was calculated as well. RESULTS: The intravenous emulsion, as a drug delivery system, may enhance the 3H quantity in liver, spleen and　 lymph system. The results also demonstrate that it can prevent the 3H from transporting to brain. The emulsion plays an important role of effectively reducing the side effects of harmine in nervous system. CONCLUSION: The weight-average overall drug targeting efficiency(Te^*) is a more reasonable evaluation parameter. The emulsion is an obviously targeted drug delivery system.