Software start-ups develop innovative software products working with disruptive technologies in time pressure and market-driven environment. Recently, User eXperience (UX) has become a hot topic that interests software teams of start-ups. However, software and UX professionals have struggled to match UX practices into the development activities, partially because of the lack of resources in the start-ups. This paper investigates how software start-ups handle UX activities during software development and how relevant UX is to these companies’ professionals. To achieve our aim, we surveyed 88 professionals who take part in software teams in star-ups, analyzing the responses using descriptive and statistical methods. From the survey results, we identified a set of challenges to be overcome in consolidating the UX work in software start-ups. By diagnosing the UX state-of-practice in start-up scenarios and identifying such challenges, our work contributes to provides relevant insights to further academic and practical studies in this field.