Online trade of CITES listed species has become a persistent threat which is difficult to measure and control. The use of online markets is growing day by the day as technology becomes more available and familiar to people of all ages and interests. Species trade can now be propagated remotely hardly without any real human interaction. We develop a quick-easy method to assess the online availability of the genus Strombocactus, a highly collectible cactus, to understand the real magnitude of this new form of threat and the possible menace it could be for these Mexican cacti. We used the Google.com site to do an online search in four languages (Spanish, English, French and German) for the offer of adult plants or seeds. We found specimens and seeds available in major online markets like ebay, amazon, cactusplaza.com and mercado libre. Plant price range from €10.00 to €30.00 plus shipping and handling. The plants were also offered in local online stores in countries like the USA, France, Germany, Australia, Czech Republic, the United Kingdom, and others; some sellers claim they have no obstacles for “shipping across countries” and others openly declare the natural localities where seeds were extracted. Only a minority of these online stores openly stated that the cacti were obtained from CITES registered nurseries or that the cacti were grown through propagules or seeds. Our method is easily transferable to estimate the illegal market for any species. There is an active online trade of Strombocactus species and other species listed in CITES without the necessary documentation. Compliance or other regulation mechanisms are needed in order to promote species conservation.