We have explored the RNA oncogene expression by three human acute lymphoblastic leukemia lines, NALM-6, MOLT-3, and REH. We compared such expression with that of normal human lymphocytes. Marked differences in the RNA expression of the third exon of c-myc, v-myb, v-Hras, N-ras, v-fes, and v-fos were found. We noted minimal or no differences in the RNA expression of v-abl, B-lym, v-erb-B, c-ets, v-fms, v-kras, v-mos, v-raf, and v-sis.