The purpose of this paper is to assess the relevance of cryptomarkets, characteristics of purchasers and possibilities for survey research by approaching users directly on cryptomarkets. Therefore a cross-country comparison of the results from the European Web Survey on Drugs (EWSD) and summarizing lessons learned during the data collection was carried out. Purchasers of drugs on cryptomarkets are still a rather small segment of all drug purchasers, and most people who use cryptomarkets also use other sources of supply to buy drugs. The percentage of people using cryptomarkets is unevenly distributed across countries and substances. Purchasers on cryptomarkets in most countries are more likely to be men and more likely, on average, to use more substances. Other characteristics such as age or place of residence do not show a consistent pattern across countries. Recruitment of respondents on cryptomarkets calls for specific techniques and procedures. Specific attention should be paid to build trust and guarantee credibility and anonymity.