We developed a high-resolution microSPECT system and investigated its performance characteristics for small animal imaging. The microSPECT system consists of a stationary compact gamma camera with interchangeable pinhole and parallel-hole collimators and vertical object rotation mechanism. The modular camera is based on a pixellated NaI(Tl) crystal array with 1.2 mm pixel size and 1.4 mm pixel pitch coupled to a 5” diameter Hamamatsu R3292 PSPMT. The pinhole collimator has a 10cm focal length fitted with keel-edge pinhole apertures with diameters of 1.0, 1.5 and 2.0 mm. The system performance was characterized by the measurements of the point source response function (PSRF) using ~300μm point sources of 99mTc. The system performance in SPECT imaging was evaluated using micro SPECT phantom and 99mTc-MDP bone scan of a mouse. The asymmetric PSRF and detectionefficiency falloff were observed for the pinhole apertures with keel-edge design when the point source was scanned from the central axis to the edge of the field-of-view of pinhole collimator. This system can achieve 1.1 mm spatial resolution using 1 mm pinhole aperture at 2.5 cm distance to the pinhole. High-resolution and high-quality SPECT images were demonstrated from imaging micro SPECT phantoms and 99mTc-MDP bone scan of a mouse.