A streamlined and effective method for RFLP analysis of DNA has been developed. Southern transfers are accomplished by alkali blotting DNA onto positively charged nylon membranes. The prehybridization step has been eliminated. The hybridization solution is composed of three cost-effective reagents: 7% SDS, 10% PEG, and phosphate buffer. By using probes that hybridize to variable number of tandem repeat loci, and RFLP analysis of one to two micrograms of genomic DNA can be achieved within five working days under normal working hours. With longer autoradiographic exposures, as little as 20-100 ng of human genomic DNA is sufficient for analysis.