Although there is no lack of empirical evidence on the determinants of genetically modified (GM) food purchase behavior, most of the available studies focus on the effects of market price and individual socio-economic characteristics. Far less is known about whether consumers will respond to environmental protection in their purchase decisions. This paper contributes to an enormous body of literature on the demand for GM food by taking biodiversity protection into account. In particular, we investigate a trade-off between consumers' willingness to pay and the conservation of biodiversity. Using a large scale choice-experimental survey dataset of 1,188 individuals, drawn from the Taiwan Genomic Survey conducted in 2011, we estimate a sequential logit model for the sequential decision making process. Our results show that demand for GM food is not simply determined by market price, but is also highly correlated with consumers' awareness of biodiversity conservation. Consumers would be less likely to purchase GM soymilk if the GM production process damages the environment. Moreover, the trade-off between market prices and conservation of biodiversity is found to be non-linear.