Assessing the impact of laws controlling the online availability of 25I-NBOMe, AH-7921, MDPV and MXE -outcomes of a semi-automated e-shop monitoring http://researchonline.ljmu.ac.uk/5432/ Article LJMU has developed LJMU Research Online for users to access the research output of the University more effectively. Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Users may download and/or print one copy of any article(s) in LJMU Research Online to facilitate their private study or for non-commercial research. You may not engage in further distribution of the material or use it for any profit-making activities or any commercial gain.The version presented here may differ from the published version or from the version of the record. Please see the repository URL above for details on accessing the published version and note that access may require a subscription. Aims: The indicator of availability has been used in the risk assessment (RA) of new psychoactive substances (NPS). This paper aims to examine the pre-and post-control availability of 25I-NBOMe, AH-7921, MDPV and MXE, which were assessed by the EMCDDA. Methods: Data were collected by a semi-automated software tool (I-TREND SASF) on e-shops in national languages (Czech, French, Dutch, Polish and English) that offered shipping of these compounds into the respective countries; frequency analysis was used. Findings: The number of e-shops selling these substances decreased between III/2014 and XII/2015 (except for AH-7921). Both increases and decreases were found on the country-level for all the compounds (except for an overall decrease for MXE). In one instance an NPS disappeared from this market in 2015 (25I-NBOMe in NL); 25I-NBOMe and AH-7921 in France and AH-7921 in Poland appeared for the first time in 2015. The shops listing AH-7921, 25I-NBOMe and MDPV in XII/2015 ranked higher in terms of ''popularity'' than in III/2014. The IP addresses were more likely to be outside the EU in 2015 than in 2014. Conclusions: We found no evidence that national-level compound bans contributed to the changes in online NPS markets. Indicators of the accessibility, availability, popularity, and IP origin should be considered in RA. Data triangulation with street markets and the darknet is needed as well as more research into the ''displacement'' and ''replacement'' effects of control laws.