In this chapter an overview is given of QTL studies performed in the species Brassica rapa. First we provide an overview of the types of molecular markers that have been used in time, and the genetic maps that have been constructed from a broad range of populations, both in terms of population type and morphotypes used for the crosses. Since the publication of the B. rapa genome sequence, numbers of molecular markers have increased exponentially. Second, an overview is given of QTL studies published in the last few years, and thereafter the QTL studies that resulted in cloning of the causal genes are presented. A brief overview is given of association mapping studies performed in B. rapa, and the chapter is concluded with proposed strategies to identify genes underlying both qualitative and quantitative traits.