The emergence of the internet has led to an information revolution that has changedindividuals social behaviour. This has resulted in changed user behaviour in digitalcommunication channels. The development has occurred at the same time as the developmentof e-commerce, which has facilitated exchange between buyers and sellers. The fashionindustry sell products that generate a high level of engagement. High-engagement productsare shared digitally between individuals and generates the phenomenon "dark social", whichis traffic from digital communication channels that web analytics can not analyze. The purpose of the study is to describe how companies in the fashion industry are affected bythe phenomenon "dark social" from a digital marketing perspective. The study is thereforedelimited to collecting empirical material from respondents who are either specialists indigital marketing or key personnel in the marketing department of companies in the fashionindustry. This delimitation has been made because products sold by companies in the industryis engaging individuals to communicate about the products. The study was based on aqualitative method in which the empirical material was collected from five respondentsthrough semi-structured interviews and questionnaires. The obtained empirical material hasbeen cross fertilized with theories about high-engagement products, web analytics,"electronic word-of-mouth" and "dark social". The challenges of "dark social" are the constraints of the companies abilities to evaluatedigital marketing, and the lack of knowledge about the phenomenon. The study shows thatcompanies in the fashion industry are currently not considering the challenges of "darksocial". On the contrary the study shows that companies should be taking the phenomenoninto account by forming an understanding and increasing knowledge about how it may affectcollected data. This is in order to make more accurate decisions regarding digital marketingstrategies. The fashion industry has been highlighted as one of the most vulnerable to thephenomenon.