Drug abuse and alcoholism in the workplace by employees have become very serious labor problems in the United States in recent years. In order to cope with these new problems, American employers in both public and private sectors have adopted numerous drug and alcoholic testing programs to screen their employees. Although these testing programs have already produced some positive results for the employers, they also raise several important legal issues. The purpose of this article is to make an in-depth examination of the emerging legal issues concerning drug and alcoholic testings of employees in the Unties States. Aside from introduction and conclusion, the main contents are divided into seven sections. Section One describes briefly several federal drug-free statutes and regulations dealing with drug testing programs in the workplace. Section Two examines several related constitutional issues raised by drug and alcoholic testings of employees. The following section deals with the relationship between several important federal fair emplovment legislation and these testing programs. Section Four analyzes the role played by labor unions regarding drug and alcoholic testings in the framework of collective bargaining system established under the National Labor Relations Act and the Railway Labor Act. Section Five delves into some other related legal issues caused by employers' drug and alcoholic testing programs. Section Six examines whether employees can utilize several common law doctrines, such as invation of privacy, defamation, emotional distress and unfair dismissal, to obtain suitable remedies from the courts. The final section tries to provide employers with several preventive measures to forestall litigations arising from drug and alcoholic testings in the workplace.