Conservatism has been present in accounting practice for a long time. Currently, the dichotomy between historical cost and fair value or between the qualitative characteristic of relevance and reliability motivate further research. Thus, in this paper we analyse whether the level of investment affects conditional conservatism in Portuguese small and medium-sized entities over the period from 2014 to 2018. The study was based on the econometric model proposed by Basu (1997), modified by Ball and Shivakumar (2005). The results indicate that these firms in general do not opt for conservative accounting practices. However, firms that report investment activities tend to be more conservative aiming at capturing investors’ confidence. Furthermore, the empirical evidence does not allow us to conclude that extreme levels of investment significantly affect conservatism. This study contributes to the debate on the relevance of conservative accounting practice at the level of investment decisions.