A heat sink for dissipating heat generated by an integrated circuit package includes a flat base 10, two vertical U-shaped heat pipes 20 and a heat dissipation body. The heat dissipation body includes a pair of side plates 40 and a plurality of fins 50 sandwiched between the side plates 40. Each heat pipe 20 has a horizontal heat absorbing portion 22 attached to the base 10, and two heat dissipation portions 24 extending perpendicularly from opposite ends of the heat absorbing portion 22 and through the side plates 40.