Purpose: The purpose of this study is to measure the technical efficiency of Japanese national universities over the period 2010-2016. In addition, the authors also sought to identify the determinants of efficiency, especially those amenable to public policy intervention. Design/methodology/approach: First, the authors ran a global intertemporal data envelopment analysis to understand the trends in efficiency for national universities over the relevant period. Following this, the authors conducted a second-stage regression using a double-bootstrapped truncated regression model to identify the possible determinants of efficiency. Findings: The authors found no evidence to suggest that technical efficiency of national universities systematically decreased or increased in response to either structural reform or a reduction to government grants. Moreover, the share of government grants, the size of universities and disciplines of study offered by the universities were statistically significant determinants of efficiency. Practical implications: The study results suggest that efficacious public policy remedies might include inter alia measures to reduce the reliance on public funding, efforts to attract more foreign students, the execution of mergers among small universities and consolidation of inefficient departments. Originality/value: This research fills an important gap in the scholarly literature with respect to Japanese national universities and identifies possible determinants to efficiency, which are amenable to remedial public policy interventions.