This book examines the problem of adverse selection in the health care insurance market. the book researches the many testings of the existence of adverse selection in the health care insurance market and examines the negative consequences which adverse selection might have in this market. The book finds enough evidence to prove the existence of adverse selection in health care insurance markets. Before proposing several solutions for the problem, the book first looks at how countries are currently dealing with the problem and if their system is effective. Individuals deviate from the rational expectations, primarily advantageous selection determines whether these deviations reduce the problem of adverse selection. There are many tools to avoid the problem of adverse selection, such as insuring all individuals and making a risk-equalization fund. Adverse selection poses as a problem in a situation where countries do not take actions to avoid it, such as the above mentioned tools.