Restriction endonuclease fingerprinting (REF) has been utilized to screen 19 of the 28 exons in the L1CAM gene using only 5 PCR reactions. The clustered exons were amplified and the PCR products were subjected to endonuclease digestion and subsequent gel electrophoresis to produce a highly informative fingerprint for each PCR product. An alteration in the fingerprint, when compared to a control, determined the specific DNA fragment containing the mutation. Sequencing of the corresponding exon and flanking region was done to determine the precise location of the mutation. Using this method we have identified 6 novel mutations in the L1CAM gene in 5 patients with X-linked hydrocephalus and 2 patients with MASA. One of the mutations was common to both a patient with HSAS and a patient with MASA. The utilization of REF will allow for easier and quicker detection of mutations in the L1CAM gene. This method should be applicable for screening other genes with multiple, clustered exons.