Using Western blot analysis and the ELISA technique, we showed previously significantly higher levels of subunit c in the urine of individuals with late-infantile neuronal ceroid lipofuscinosis (LINCL) and some patients with juvenile NCL (JNCL) [Wisniewski et al., J. Inherited Metab Dis 17: 205-210, 1994]. In an attempt to develop a diagnostic screening test for NCL based on detection of this biochemical marker in urine, we analyzed, using the blotting technique, urine from 7 infantile NCL (INCL), 17 LINCL, and 19 JNCL cases, 30 obligate heterozygotes, and 60 control cases. This analysis confirmed our former data showing significantly higher levels of subunit c in the urine from all LINCL and some JNCL cases. No false positive results were found. This simple analytical method may serve as a fast, non-invasive screening test for NCL.