The quad-HIDAC small animal PET camera is a quadratic array of high-density avalanche chambers; the camera described in this publication consists of 16 modules. We present the system response using point and line sources and a mouse phantom. The quad-HIDAC camera exhibits a count rate stability of better than 1% and linearity of response to coincidences up to 2.2 x 10(5) cps at 16 MBq activity. Corrected for deadtime and random coincidences, the efficiency for the line source is 0.011, of which unscattered coincidences yield 0.009. The scatter fraction originating from the detectors is 0.22. Absorption within the mouse phantom was 20% and the scatter fraction increased to 0.29. Resolution is uniform within the entire field-of-view, which is 28 cm axially and 17 cm radially. Reconstruction of a point source yields a resolution of 1.1 mm FWHM for all three components. The performance of the camera demonstrates its excellent suitability for the functional imaging of small animals.