The introduction of market forces into higher education (i.e. marketization) in recent decades goes along with a sharp decline in tenured positions offered, accompanied by polemic voices against tenure. The main claim, that tenure reduces the productivity of senior faculty, has not been thoroughly tested, with existing scarce evidence being controversial. We tested this hypothesis by analyzing the number of publications of 2136 currently full professors of natural sciences, drawn from 123 universities distributed in 15 countries, during the period 1996 to 2014. Our results showed that long-term productivity of full professors increased, irrespectively of subject field, geographic area, and university rank. This suggests that tenure does not lead to motivation loss and academic deadwood. Our results have policy, academic, and ethical implications related to human resource management, academic freedom, and educational quality, and tenure polemicists should find an argument other than lowered post-tenure productivity to support their stand.