A recent investigation into prion protein (PrP) deposition in cases of Creutzfeldt-Jakob disease (CJD) has suggested that the spinal cord is affected in some cases of this disease. In an attempt to measure this phenomenon we have used quantitative image analysis techniques to assess the amount of PrP deposited in the spinal cords of three different cases of CJD. By using an automatic method of image intensity threshold setting we have measured the tissue area occupied by PrP in a non-subjective manner. The ranking of these different cases has confirmed that suggested by visual inspection. This analysis shows a substantial variation in the quantity of PrP positivity observed when a panel of different PrP antibodies was compared, confirming early findings. The distribution of PrP across the spinal cord has also been mapped using the image analysis system.