Electronic linkage between pathology data sources and other information systems has not realised its full potential benefits due to the poor quality of histopathology coding. This study showed that 38% of a sample of 158 pathology reports were coded accurately. Of the incorrectly coded reports, 25% had the potential to distort published cancer incidence figures. The incidence figures of the most common cancers are less likely to be affected by coding errors. Areas in which all errors, both topographical and morphological, could have significant impact include examining resource allocation at directorate level and adjusting outcome indicators for casemix. This study concludes that electronic linkage between histopathology systems and cancer registries is not sufficient to improve the quality of registration data. As cancer registries become more dependent on computerised information provided through hospital information systems, registries need to be aware of poor quality data and put in place appropriate quality assurance measures specifically tailored to support electronic cancer registration. Purchasers and providers need to be aware that incomparable datasets could be produced if other bodies use computerised pathology datasets without first validating the data.