Abstract: The clinical values of tumors positive imaging with 99 Tc m MIBI is evaluated. The imaging results of twenty one patients with tumors pathologically determined are studied in 15～30 min after injection of 99 Tc m MIBI using GE SPX 6 SPECT. The ratio of tumor to background(T/B) is calculated, and the positive results are determined when T/B≥1.5. The positive results also are obtained when space occupy lesion(SOL) of liver in colloid imaging are filled in 99 Tc m MIBI imaging. Seventeen of twenty one (17/21) patients have malignant tumors and four of twenty one (4/21) patients have benign tumors in pathologic diagnosis. In which fifteen of seventeen (15/17) patients with malignant tumors are positive, two of seventeen (2/17) patients with malignant tumors are negative, and four of four (4/4) patients with benign tumors are negative diagnosed by SPECT with 99 Tc m MIBI. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of tumor positive imaging with 99 Tc m MIBI are 88%, 100%, 100%, 66.7% and 90%, respectively. It shows that tumor positive imaging with 99 Tc m MIBI appears to be a useful method for diagnosis of malignant tumors.