1. DSC has high accuracy. It has a prediction accuracy of 70.1% (per residue) on a standard set of 126 proteins. This percentage was confirmed by the recent CASP2 blind prediction challenge (see below). 2. DSC is based on simple linear statistics. Existing highaccuracy prediction methods are 'black-box' predictors based on complex non-linear statistics [e.g. neural networks in PHD (Rost and Sander, 1993) and nearestneighbour methods in NNSSP (Salamov and Solovyev, 1995)]. 3. DSC's accuracy is predictable a priori. This permits evaluation of the utility of the prediction, e.g. it is possible accurately to predict chains that have a mean accuracy of >80%. 4. DSC source code is freely available (in C). This allows DSC to be easily ported to other systems and to be used on proprietary sequences (e.g. DSC is running in-house at Glaxo Welcome pic). 5. DSC has a prediction server (see below). This server can generate its own sequence alignments.