An LED lamp includes a heat sink (10), a plurality of heat pipes (20) mounted on outer sidewalls (120) of the heat sink, and a plurality of LED modules (30) attached on the outer sidewalls of the heat sink with a portion of each LED module contacting a corresponding heat pipe directly. A plurality of fins (14) extend inwardly from an inner wall of the heat sink in a manner such that a through hole (16) is enclosed by the fins, thereby providing an airflow passage axially through the heat sink. By the use of the heat pipes, heat generated by the LED modules can be transferred to the heat sink evenly, whereby the heat can be dispersed to ambient air efficiently and rapidly.