Easy applicability of modern microfabrication technology to electrophoresis microchips has initiated a rapidly moving interdisciplinary field in analytical chemistry. Electric field-mediated separations in microfabricated devices are significantly faster than conventional electrophoresis methods and are usually completed in seconds to minutes. The flexibility of fluidic manipulations in electrophoresis microchips allows the use of a variety of separation techniques and conditions. In this study, large-scale genotyping of the repeat polymorphism in the regulatory (promoter) region of the serotonin transporter gene 5-HTT linked polymorphic region (5-HTTLPR) was attempted using polymerase chain reaction (PCR) amplification followed by rapid microchip electrophoresis analysis of the amplicons.