A quadruplex reaction has been developed which amplifies the short tandem repeat (STR) loci HUM-VWA31/A, HUMTHO1, HUMF13A1 and HUMFES/FPS. Detection of the PCR products employs denaturing polyacrylamide gels coupled with fluorescent-based technology. This system has been evaluated for use in routine forensic casework and has been shown to be both robust and reproducible. The quadruplex reaction is as sensitive as the commercially available HLA DQ alpha Amplitype typing system and can be used on both degraded and aged material. The problems of environmental contamination have been shown to be limited provided strict procedural practices are followed-i.e. physical separation of sample extraction and amplified products; the use of dedicated equipment such as pipettes; the separation of amplification preparation area. The ability of the system to detect mixtures and the successful analysis of case stains has shown that this system is well suited as a tool for forensic investigation.