A snapshot of the sale of fentanyl and its analogues across several popular darknet markets between 2 January and 27 March 2019 reveals the amount, types and physical forms available. Of the 127,541 unique drug listings identified, 13,135 were opioids (10.3% of all drugs), of which 1,118 (0.876% of all drugs) were fentanyl or its analogues. Between 27.3 and 39.3 kilograms of fentanyl and its derivatives were available over the period. The average price of fentanyl was A$99 per gram, while carfentanil was A$26.8 per gram. The shipping methods, cross-market operations and product specialisation of the 303 active fentanyl vendors on these darknet markets are also described.