Abstract: A method of analyzing DNA fragments separated electrophoretically is presented. The method includes the use of an expert system that interprets raw or preprocessed signal from the separation. The expert system can be used for real-time base-calling, or applied offline after data acquisition is complete. The expert system is directly applicable to all types of electrophoretic separation used for DNA sequencing, i.e. slab gel, capillary and microchip. Each lane of a multiplex system can consist of 1 to 4 (or even more) different fragment labels. The expert system may also be used with other base-coding schemes, such as those in which more than one base is labeled with a given dye, but the amount of label is different for each base. When the presently disclosed method is applied to DNA sequencing, the resulting interpretation comprises a DNA base sequence with numerical confidences assigned to each base.