A bed frame comprising T-shaped side rails provides support for a box spring and mattress. The T-shaped side rails provide more resistance to twisting and bowing and enables the overall bed frame to support more weight with less deflection than the convention L-shaped side rails. The T-shaped side rails may be two L-shaped angle irons affixed together or a unitary T-shaped member that can also be used for other structural components of the bed frame such as a center beam. The vertical flange of the T-shape can be non-linear. In a further embodiment, the side rails are comprised of a metal skin enclosing a hollow area with a horizontal, flat shelf for supporting the box spring and a contiguous vertical surface generally at a right angle to the horizontal shelf to retain the box spring in it desired position.