Radiopharmaceuticals are used in procedures of nuclear medicine for the diagnosis and treatment of illnesses. Fluorine-18(18 F) is a positron emitter produced in cyclotron. It is used to get 18 fluorodeoxyglucose (18 F-FDG) that is a radiopharmaceutical utilized in the positron emission tomography scan. The aim of this work was to evaluate the in vitro effect of an extract of Ginkgo biloba extract (EGb) on the distribution in blood cells (BC) and plasma (P) compartments and on the binding to the blood constituents of the 18 F-FDG using precipitation with trichloroacetic acid (TCA). EGb was not capable to interfere on the distribution of the 18 F-FDG on the BC and P compartments. However, this extract was capable of interfering significantly (p<0.05) on the fixation of the 18 F-FDG on IF-P (in all the concentrations tested, P<0.05) and IF-BC in 1% TCA concentration from 14.04±1.13 to 10.23±1.92 (40mg/ml, EGb) and to 9.35 ±1.57 (400mg/ml/EGb), in 5% TCA concentration from 14.83±3.78 to 11.15±1.64 (40mg/ml, EGb) and to 10.23±1.6 (400mg/ml, EGb). In conclusion, the analysis of the results indicates that the EGb was not capable to interfere on the distribution of the 18 F-FDG on P and BC compartments, however, alter the fixation of the 18FDG on IF-P and IF-BC.