The effect of implantable drug delivery systems on computed tomography (CT) and magnetic resonance imaging (MRI) was investigated in a phantom and in two patients. The implantable systems of identical construction consisted either of medical grade titanium alloy or stainless steel. Images of a phantom showed artefacts of the stainless steel port in both CT and MRI. These artefacts were substantially reduced in images of the titanium port. Similar results were found in situ in two patients.