Natasha Leighl, MD, MMSc, FRCPC, Princess Margaret Cancer Center, Ontario, Canada, discusses whether tissue biopsy will still be needed when liquid biopsy is fully implemented in clinical practice. An advantage of tissue biopsy is that clinicians can know which mutations have come from a specific tumor, whereas in liquid biopsy there could be a hidden cancer that is the cause of the mutations found in plasma. Prof. Leighl suggests that it is important to use both techniques in conjunction with each other. This interview took place at the International Society of Liquid Biopsy (ISLB) 2021 Virtual Meeting.