This article reviews the most important contributions to literature on “public debt-economic growth” relationship. Most relevant studies are empirical. Some of them are based on causality tests, albeit with no clear conclusion as to what the causes and what the effects are. We also indicate important gaps, which have not been considered and these are either periods of economic crises or “secular stagnation” phenomena. We suggest that policy makers and investors should reconsider not only the so-called 90%“threshold hypothesis” but also the causality itself, because there is no necessary theoretical consensus so far.