The research purpose was to examine the problems of companies in implementing Activity-Based Costing and, in particular, to analyze the differences in assessing the level of these problems perceived by organizations using the system, considering its implementation, those which had not considered it, and those which had rejected it. The research showed that the problems with ABC implementation seen by adopters were considerably smaller compared to the other groups. A similar difference was noted between enterprises that were considering the implementation of the ABC system (and not considering it at all) and those that rejected it. The last group perceived implementation problems to be bigger than was the case in the groups which were still considering implementation or had not considered it at all. The findings seem to support the view that companies are making ABC implementation decisions rationally. On the one hand, when the problems perceived during implementation are relatively small, the company adopts ABC. On the other hand, when a company perceives the implementation problems as being quite significant, it rejects the implementation. In the middle of the scale are companies considering the implementation of ABC and others that are not thinking about it at all. They assess the perceived problems as moderate and are not in a position yet to decide for or against ABC implementation. There could also be an alternative explanation for the research results. It may be the case that companies, which have not implemented ABC overestimate the implementation problems.