The separation by capillary electrophoresis of five ecstasy derivatives has been evaluated by means of experimental designs. A full-factorial design and a central composite design were employed to optimize the experimental conditions for a fast separation. With a conventional capillary (62.5 cm length) analytes were separated in less than 8 min. When the capillary length was reduced the analysis time decreased substantially. Comparisons were made between different procedures (e.g. working at a constant field or at constant voltage) and finally, a fast separation of five Ecstasy derivatives was achieved in 1 min.