Subsurface fluorescence molecular tomography (FMT) has promising potential for noninvasive characterization of molecular and cellular activities in small animals by tomographic means in reflectance geometry. In this work, subsurface FMT is employed to monitor the therapeutic response of cisplatin in tumor-bearing mice in vivo. The localization and quantification accuracy of subsurface FMT are demonstrated in phantom. In the in vivo study, the red fluorescent protein activities not only on the surface but in the interior tumor are tracked three-dimensionally during the antitumor treatment.