Demand for tiger parts and products has fuelled the poaching of wild tigers. As the supply of wild tigers has become scarce, tiger farming has emerged as an alternative source and proliferated in several Asian countries with unclear implications of a legalized trade in farmed tigers on wild tiger demand. We conducted a choice experiment with 228 Vietnamese tiger bone glue consumers investigating their preferences and trade-offs for different attributes of their purchase choice, including legality, source, purity, and price. We calculated consumers' willingness to pay for each attribute level under the current trade ban and in a hypothetical legal trade. Consumers preferred and were willing to pay more for wild than farmed tiger glue and a higher proportion of tiger bone in the glue. Consumers also preferred legal over illegal sufficiently for most to switch from illegal wild to legal farmed tiger. Hence, a legal trade will shift preferences significantly towards farmed tiger glue from legal sources but will not eradicate demand for wild tigers, likely leading to the parallel operation of legal and illegal markets. We discuss the implications of the results for conserving wild tigers through efforts to manage demand in Vietnam.