The research took place in Japan. DNase I phenotyping from saliva stains had previously been unsuccessful due to low enzyme activity and heavy contamination. The present research extracted salivary DNase I from stains using phosphate bufer containing Nonidet P-40. Extracts were purified using Phenyl Sepharose CL-4B gel. Electrophoresis was performed, and DNase I was successfully phenotyped. All the DNase I phenotypes obtained from saliva stains using this new method were identical to the phenotypes determined from urine samples. Moreover, this method correctly phenotyped DNase I from saliva stains that had been stored for more than 3 months at room temperature or at 37 degrees centigrade. Findings suggested that DNase I polymorphisms provide useful information for forensic characterization of saliva stains. Figures, table, and 18 references (Author abstract modified)