Background: Internet and smartphones enable people to purchase online independent of time and place, and this have resulted in that impulsive purchases on the internet have increased. Different generations have been described to be more or less susceptible to impulse buying. Generation Y, the first generation that grew up with technology, have generally been described as impulsive, while Generation X, who were introduced to technology later in life, have been described as more rational. Further, consumers’ impulsive buying behavior has shown to be crucial and common, especially within the fashion industry. Purpose: The purpose was to investigate how Gen Y purchase apparel impulsively online compared to the older Gen X. Also, which one of them that make most apparel purchases online, and which one of them who do most web browsing of apparel. Further, the authors wanted to investigate how four different factors affect the generations’ impulsive buying behavior in the case of apparel online. These were based on an adjustment of the Revised CIFE-model. Method:  This research was conducted through a quantitative method, and seven hypotheses were formulated based on the theory. An online survey was constructed and shared through social media, and the final sample consisted of 709 respondents from both Gen X and Gen Y. These responses were analyzed through SPSS, and the hypotheses were tested by combining questions. Conclusion: The results showed that Gen Y are browsing more apparel online than Gen X, and also that they more often purchase apparel impulsively online. However, Gen X buy more apparel online in general. The findings further showed that Gen Y are more affected than Gen X by external trigger cues, normative evaluation, and internal factors when it comes to impulsive e-purchases of apparel. There was no difference between the generations’ impulse buying tendency. Findings from the open-ended questions showed that Gen X often are affected by advertising, while Gen Y are more affected by influencers. Sales and special offers influenced both generations.