Grading bias against boys may be one of the reasons why boys underperform in school compared to girls. This study assesses the causal effect of blind grading of boys relative to girls using difference-in-differences methods and exploiting two separate identification strategies: a unique full cohort natural experiment providing exogenous variation in blind grading, and a field experiment where the exact same exam papers are scored twice (blind and non-blind). Even though the two strategies hinge on different assumptions, the results persistently suggest against the existence of systematic gender biases in non-blind evaluation. The results are robust to different model specifications.