Software-as-a-Service (SaaS) is said to become an important cornerstone of the Internet of Services. However, while some market research and IT provider firms fervently support this point-of-view, others already conjure up the failure of this on-demand sourcing option due to considerable risks associated with SaaS. Although there is a substantial body of research at the intersection of traditional and on-demand IT outsourcing and risk management, existing research is virtually silent on analyzing the risks of SaaS. This study thus seeks to deepen the understanding of a comprehensive set of risk factors affecting the adoption of SaaS and discriminates between SaaS adopters and non-adopters. Grounded in perceived risk theory, we developed a research model that was analyzed with survey data of 379 firms in Germany. Our analysis revealed that security risk was the dominant factor influencing companies’ overall risk perceptions on SaaS-based sourcing. Moreover, we found significant differences between adopters’ and non-adopters’ perceptions of performance and financial risks. Overall, this study provides relevant findings that potential and actual SaaS clients may use to better assess SaaS-based offerings. For SaaS providers, our study gives important factors to emphasize when offering SaaS services to companies in different stages of the technology adoption lifecycle.