This article presents a survey of recent theoretical, as well as empirical, contributions concerning business investments, which help to explain the investment decision making of companies. These contributions emphasize the relevance of idiosyncratic factors affecting investment decisions such as the degree of irreversibility and uncertainty, interactions between these factors may generate an opportunity cost equivalent to the exercise of an option and so they add an important dimension to the neoclassical theory of investment (also called standard or orthodox theory of investment). This theory has not recognized the important qualitative and quantitative implications of this interaction, what can explain some of its failures. We investigate the irreversibility of investments and the impact this has on the nature of the relationship between investment and uncertainty in the way of empirical analysis. The empirical analysis uses firm – level data and is based on a survey of 53 automotive suppliers, which was carried out during the year 2011. We find supportive evidence for the fact that uncertainty is negatively associated with planned investments of the companies surveyed, which remains true also in the presence of irreversibility. At the end we demonstrate the core of the real options approach in a form of a practical example.