Recently, WSJ-1, a stable bioengineered strain, constructed by integrating the 4"-isovaleryltransferase gene into the chromosome of Streptomyces spiramyceticus F211), was obtained. A group of 4"-acylspiramycins designated Shengjimycins were isolated from the culture of this strain. Structures of eleven components of Shengjimycins were determined, which are summarized in Fig. 1. In this paper, we report isolation, physico-chemical properties, and structure identification of Shengjimycins.