The Liu Wei Di Huang Wan is a formula of a traditional Chinese medicine that is used to treat asthma patients and has been shown to have several important properties,such as antioxidant and free radical scavenging activities.The influence of an extract of Liu Wei Di Huang Wan on the labeling of blood constituents with technetium-99m was investigated.Anticoagulated blood(Wistar rats) was incubated with the extract,stannous chloride and technetium-99m,as sodium pertechnetate.Samples were centrifuged and aliquots of plasma and blood cells were separated and precipitated with trichloroacetic acid,to obtain soluble and insoluble fractions of the blood constituents.The percentage of radioactivity(%ATI) in all the fractions was determined.The analysis of the results shows that the extract at the highest concentration used(70 mg/mL) decreased significantly(P<0.05) the %ATI(from 96.48 ± 1.19 to 54.46 ± 7.38) on blood cells compartment,(from 81.11 ± 4.15 to 61.33 ± 4.74) on insoluble fractions of blood cells and(from 65.91 ± 2.44 to 13.15 ± 3.62) on insoluble fractions of plasma.In conclusion,the results suggest that the substances present on this extract can alter this labeling process,probably due to(i) redox properties(antioxidant and chelator activities) and/or(ii) specific actions in the binding sites where the 99mTc would be bound on the blood constituents.As a consequence,precaution is suggested on the interpretation of the nuclear medicine results from performed with blood constituents labeled with 99m Tc in patients that have undertaken LWDHW,although the current findings were obtained in experimental animal models. The Liu Wei Di Huang Wan is a formula of a traditional Chinese medicine that is used to treat asthma patients and has been shown to have several important properties, such as antioxidant and free radical scavenging activities. The influence of an extract of Liu Wei Di Huang Wan on the labeling of blood constituents with technetium-99m was investigated. Anticoagulated blood (Wistar rats) was incubated with the extract, stannous chloride and technetium-99m, as sodium pertechnetate. Samples were centrifuged and aliquots of plasma and blood cells were separated and precipitated with trichloroacetic acid, to obtain soluble and insoluble fractions of the blood constituents. The percentage of radioactivity (% ATI) in all the fractions was determined. The analysis of the analysis of the results that that the extract at the highest concentration used (70 mg / mL the% ATI (from 96.48 ± 1.19 to 54.46 ± 7.38) on blood cells compartment, (from 81.11 ± 4.15 to 61.33 ± 4.74) on insoluble fractio ns of blood cells and (from 65.91 ± 2.44 to 13.15 ± 3.62) on insoluble fractions of plasma. In conclusion, the results suggest that the substances present on this extract can alter this labeling process, probably due to (i) redox properties (antioxidant and chelator activities) and / or (ii) specific actions in the binding sites where the 99mTc would be bound on the blood constituents. As a consequence, precaution is suggested on the interpretation of the nuclear medicine results from performed with blood constituents labeled with 99m Tc in patients that have committed LWDHW, although the current findings were obtained in experimental animal models.