By the sixteenth century variolation to prevent smallpox was an elaborate and fairly well known medical technique in China. By the middle of the nineteenth century knowledge of this procedure had spread to several countries in East and Southeast Asia, including Japan and Vietnam. There is evidence that techniques used in Chinese style variolation shaped the practice of vaccination by indigenous vaccinators in Japan after the Dutch introduced vaccinia and the techniques associated with its use and propagation from the Dutch East Indies. Indeed, viable vaccinia was finally, after decades of failed attempts, successfully imported to Japan only after Japanese physicians familar with Chinese style variolation suggested that the Dutch send cowpox scabs rather than lymph. Transport of smallpox scabs, containing attenuated smallpox virus, was standard practice for Chinese variolators. Conversely, there is also evidence that procedures used in vaccination, which had been introduced from Macau in 1821, shaped the practice of Chinese style variolation in Vietnam. Indeed, Vietnamese physicians practicing variolation were observed to made cuts in the skin to insert the variolus material much as cuts were made by western physicians practicing Jennerian vaccination. Using evidence from archival materials held in Ha Noi, Lisbon, Paris, and Singapore this essay will explore this cross-fertilization between traditional Chinese techniques and practices and introduced western medical procedures.