In this study, high public external costs are taken as responsible for Turkey's underdevelopment. Main reasons for such public costs are political instability, extravagancy, no rule or bad rule, which impede the growth, lack of transparency, centralization, rent seeking, lack of control and corruption. As a result, due to such costs, Turkish goods become more expensive, thus loose competitive strength at the international market. Hence, Turkey's overall economic performance falls as well. Turkish economy would be better off in the absence of such a public cost which about 184,2 billion US dollars for the period of 1990-99, as put forward in this study.