Heat transfer by mixed convection in a rod bundle occurs when convection is affected by both the buoyancy and inertial forces. Mixed convection can be assumed when the Richardson number (Ri = Gr/Re2) is on the order of unity, indicating that both forced and natural convection are important contributors to heat transfer. In the present study, data obtained from the Rod Bundle Heat Transfer (RBHT) facility was used to determine the heat transfer coefficient in the mixed convection regime, which was found to be significantly larger than those expected assuming forced convection based on the inlet flow rate. The inlet Reynolds (Re) number in the tests ranged from 500 to 1300 while the Grashof (Gr) number varied from 1.5x 105 to 3.8x106 yielding 0.25 < Ri < 4.3. Using results from RBHT test along with the correlation from the FLECHT-SEASET test program for laminar forced convection, a new correlation for mixed convection in a rod bundle is proposed. The new correlation accounts for the enhancement of heat transfer relative to laminar forced convection.