This paper examines how employment protection legislation influences corporate R&D investment. With a sample of 113,228 observations across 23 OECD countries from 2001 to 2018, I document that firms in strong employment protection legislation have lower R&D expenditure and investment efficiency. In addition, I find that the effect of employment protection on R&D expenditure is stronger in financially constrained firms but the effect of employment protection on R&D investment efficiency is stronger in financially unconstrained firms.