Only one drug (sorafenib) is approved for the treatment of advanced hepatocellular carcinoma (HCC), but alternatives are urgently needed. The safety of nivolumab (PD-1 immune checkpoint inhibitor) was tested in a phase I/II, open-label, dose escalation and expansion trial (CheckMate 040), in patients with or without viral hepatitis and as first-line or second-line (after sorafenib) therapy. Nivolumab had a manageable safety profile, with acceptable tolerability. Moreover, the objective response rates (range 15–20%) combined with the substantial reductions in tumour burden indicated the potential of nivolumab as HCC therapy. Results of the ongoing phase III trial for nivolumab versus sorafenib in advanced HCC are awaited.