Buying illegal drugs through the internet captured the public imagination after the emergence of Silk Road in 2011. Silk Road, and its successors that followed (after Silk Road was shut down by the FBI in 2013), provide a means to purchase illicit drugs online and have them delivered via parcel post. These online markets are known as ‘cryptomarkets’ because they rely upon encryption technologies: anonymising networks (Tor) and virtual currencies (Bitcoin). Relatively high rates of participation in cryptomarkets have been reported in Australia: in a study of the cryptomarket Agora, Australia had the highest rate of drug retailers per capita. Consistent with high rates of cryptomarket use, successive reports from the Australian Crime Commission illustrate exponential growth in the detection of illicit drugs in the parcel post destined for Australians. There is also evidence that internationally, cryptomarkets are expanding: they generated sales upwards of $180M USD in 2015, doubling their 2013 sales volume. Cryptomarkets represent an innovation in drug supply and have “profound implications” for global drug markets according to the United Nations Office on Drugs and Crime, but their influence on the overall harms associated with illicit drug use is unknown. This project seeks to redress this significant gap, and inform policy makers about the nature and extent of health outcomes from drug cryptomarkets, globally and specifically for Australians.