The goal of the BioASQ challenge is to push research towards highly precise biomedical information access systems. We aim to promote systems and approaches that are able to deal with the whole diversity of the Web, especially for, but not restricted to, the context of bio-medicine. The third challenge consisted of two tasks: semantic indexing and question answering. 59 systems by 18 different teams participated in the semantic indexing task (Task 3a). The question answering task was further subdivided into two phases. 24 systems from 9 different teams participates in the annotation phase (Task 3b-phase A), while 26 systems of 10 different teams participated in the answer generation phase (Task 3b-phase B). Overall, the best systems were able to outperform the strong baselines provided by the organizers. In this paper, we present the data used during the challenge as well as the technologies which were used by the participants.