The paper reports on the installation and operation of an anti-Compton shield inside the cryostat of a Si(Li) detector. The shield is used for the suppression of γ-ray induced background in PIXE spectra. For the initial experiments presented, a plastic scintillator was employed as a shield. It was mounted behind the Si(Li) crystal, surrounding the cold finger. Initial tests showed a 6% suppression of the Compton background in the interval 6–32 keV of the PIXE spectrum, both for 662 keV γ-rays from a 137 Cs source and for 122 keV γ-rays from a 57 Co source. The details of the system and the potentials of the technique are presented and discussed.