Skin fibroblasts from normal and cystinotic individuals were incubated in the presence of S35-Cystine and the intracellular complement of labeled metabolites subsequently examined by high voltage paper electrophoresis. Aside from the expected appearance of a prominent cystine peak in extracts from cystinotic cells there was no signficant difference in labeling patterns of normal and abnormal cell lines. These results are consistent with earlier indications that the excess cystine storage seen in cystinosis is not the result of an enzyme defect remote from cystine along the known catabolic pathway of this amino acid.