jats:sec <jats:title content-type="abstract-subheading">Purpose</jats:title> jats:pThe purpose of this paper is twofold: to investigate the existence of different degrees of returns to scale in low-tech and high-tech manufacturing industries; and to examine whether the degrees of returns to scale change through time.</jats:p> </jats:sec> jats:sec <jats:title content-type="abstract-subheading">Design/methodology/approach</jats:title> jats:pThe empirical investigation implemented in the paper uses data from the EU KLEMS Database, covering a sample of 12 manufacturing industries in 11 OECD countries over the period 1976-2006. The investigation employed two different estimation methods: instrumental variables and system GMM. The robustness of the results was assessed by employing two different specifications of Kaldor-Verdoorn’s Law, by using lags and five-year averages to smooth business-cycle fluctuations, and by dividing the sample into two time periods.</jats:p> </jats:sec> jats:sec <jats:title content-type="abstract-subheading">Findings</jats:title> jats:pThe results reported in the paper provide strong evidence in support of the hypothesis of substantial increasing returns to scale in manufacturing. The investigation suggests that high-tech manufacturing industries exhibit larger degrees of returns to scale than low-tech manufacturing industries. Finally, the analysis revealed also that the magnitude of the returns to scale in manufacturing have increased in the last decades, driven by increases in the magnitude of returns to scale observed in high-tech industries.</jats:p> </jats:sec> jats:sec <jats:title content-type="abstract-subheading">Originality/value</jats:title> jats:pNo previous work has assessed the hypothesis that increasing returns to scale vary according to the technological content of industries. Moreover, no previous work has used system GMM or data from EU KLEMS to test Kaldor-Verdoorn’s Law. Most importantly, the findings of the paper present new evidence on the degree of returns to scale in high-tech and low-tech manufacturing industries.</jats:p> </jats:sec>