Our eight morbidity measures are derived from four morbidity descriptive systems: 17 chronic diseases in the Quality and Outcomes Framework (QOF); 17 chronic diseases in the Charlsons cheme; 114 Expanded Diagnosis Clusters (EDCs); and 68 Adjusted Clinical Groups (ACGs). The Charlson measures have the worst performance but still improve markedly on models containing only age, gender, deprivation and practice effects. The EDC measures perform best followed by the QOF and ACG measures. In general,for a given disease description system, counts of diseases and sets of disease dummy variables have similar explanatory power. Sim-ple counts of EDC or QOF conditions perform better than the more elaborate ACG multi morbidity measure.