A previous report studying the properties of A. atlas silk fibers immersed in liquid media has reported con- siderably different amino acid composition [21]. In that report, A. atlas silk was reported to contain 40.7 % gly- cine, 18 % alanine and 8.8 % serine as the major amino acids compared to 22.2, 45 and 6.8 %, respectively in this research. However, the total glycine, alanine and ser- ine in A. atlas previously reported and found in this re- search are similar at 74 and 67.5 %, respectively. In the previous study by Perez-Rigueiro, it was suggested that glycine, alanine, serine and threonine exist in the crystalline region and all other amino acids exist in the amorphous region. The ratio of amino acids in the crys- talline and non-crystalline regions was called the disor- der ratio and related to the properties of the fibers [21]. The variations in the amino acid contents of A. atlas silk in the previous report and current research should be due to habitat of the insects, rearing conditions and dif- ferences in the methods used to determine the amino acids.