The use of Internet by employees at the workplace involves risks both for the employer and the employees. As recent studies show, employees use their business computer to surf the web for personal purposes during the working hours. This lead to a supplemental cost for their employer. In addition, the networks are infested by viruses and business spies attracted by the data of the company for different reasons. Considering the risks, the employer has legitimate interests in monitoring his employees during the working hours but the use of poweful monitoring programs results in a high risk of invasion of employee's privacy. In the USA, constitutional and common law doctrines provide protection for employee privacy right. In France, employee's privacy right are ensured both by the 1950 treaty of the European Council, the Constitution and the civil code. Although both the USA and France protect employee's privacy rights at the workplace by similar rules, French and American courts have adopted opposite views on the subject of employee's privacy right at the workplace. This essay aims at comparing the differences between the French and US system of laws in balancing the employers' interest versus that of the employee.