The aim of the article is to prove that companies cooperate not only because they wish to, but also because they are forced to do it. Moreover, It turns out that sometimes firms cooperate in strategic alliances with partners which were not selected, but appeared coincidentally. The article identifies market and law circumstances which especially force companies to cooperate. In addition to this, it gives the examples of how strategic alliances are formed by coincidentally matched companies. It tries to estimate how these negative circumstances influence the performance of cooperation. The findings base on case studies, which were mainly prepared from the interviews with the management of firms. The main conclusion of the article is that both compulsory and coincidental cooperation is usually successful, especially when firms have strong motivation to maintain cooperation, can limit their opportunism and are able to show some understanding to the difficult position, in which they found themselves.