Determined sequences of 384 randomly selected clones in a PCR-based cDNA library of Antheraea yamamai could identify expressed sequence tags (ESTs) of highly expressed gene. One EST (fibroin) appeared 15 times, one EST (40S ribosomal protein S18) twelve times, one EST (ribosomal protein S24a) eleven times, ten times (ribosomal protein S8), nine times (60S ribosomal protein L10A), seven times (60S ribosomal protein S15A, S17, S17 and seroin), six times (ribosomal protein S8), five times (ribosomal protein S24, mariner transposase and P8 protein), four times (serpin 2), three times (heat shock protein 70 and poly A binding protein), and the remaining 6 ESTs twice (amylase, KIAA1006, elongation factor-1, transposon mag, translation initiation factor 4C, QM protein, transposase). Therefore, the 94 EST make it possible to identify 24 redundant clones that are candidates for highly expressed genes in posterior silk gland of this insect. The 24 redundant EST clones were identified in GenBank, but none of them was related to A. yamamai, suggesting that there are many unidentified genes which are highly expressed in the A. yamamai genome.