A study of fully developed flow and heat transfer in elliptical ducts has been made. In the experimental work with water (Pr~6.5), friction factors for pipes with aspect ratios equal to O.316 and 0.415 have been obtained over a Reynolds no. range 10³− 30.10³. Average local Nusselt numbers in turbulent flow in a stainless steel pipe of aspect ratio 0.284 have been measured for a maximum Reynolds no. and maximum average heat flux of 70.10³ and 4.15 W/cm² respectively. An empirical heat transfer correlation for the particular geometry and conditions is presented.