Re-qualification as a part of validation is the task performed to identify or check that utilities, equipment and ancillary systems can operate within limits for their intended use. Equipment qualification is a key element in the pharmaceutical quality system. In recent times regulatory agencies are more focusing on qualification of equipment. Re-qualification of the equipment starts from design of the equipment based on the user requirement specification and functional requirement specification. The review article provides information on design qualification which is done to identify whether the proposed design of facilities, system and equipment is suitable for intended purpose, installation qualification which is done to check whether the equipment is built and installed in compliance with design specification, operational qualification in which the process parameters shall be challenged to assure that product meets all requirements and finally performance qualification to demonstrate that the process will produce acceptable product consistently under normal operating conditions.