Magnetohydrodynamic (MHD) effect on heat transfer in liquid lithium annular flow was investigated with an emphasis on heat transfer enhancement and local turbulence. A test section was made of 10 mm heater pin and 2 in. B pipe of 304SS. The experiment covers ranges of U = 0.1-3 mls (Re = 4 x 10(3) - 1.4 x 10(5)), B = 0-0.8 T (Ha = 0-3 x 10(3)). The heat transfer was observed to increase over a region of St from unity to 100, and the peak value was 5-10% higher than that for B = 0 T. This was explained as a result of local turbulence enhancement in the vicinity of the heating wall. A new concept of heat transfer diagram was proposed with considering a current load factor of the test channel.