Software engineers use requirement-to-method trace matrices to indicate the methods implementing different system requirements. Requirement-to-method trace matrices pinpoint the exact method implementing each requirement, which facilitates software maintenance and bug fixing. The code structure of a system can be used to make predictions about requirement-to-method traces. In this paper, we present a data set documenting the requirement-to-method traces as well as the code structure (methods, variables, etc.) for four open source systems. The code structure was obtained by parsing the systems under consideration and extracting the methods, variables, etc. The requirement-to-method trace matrices were obtained by resorting to students as well as to the original developers of the systems who provided us with the list of requirement-to-method traces.