This paper presents a parametric analysis of the performance of internally finned tubes in turbulent forced convection for application to heat exchangers. The analysis compares the performance of an internally finned tube exchanger with that of an exchanger having internally smooth tubes. The calculations are performed for three important design cases. By variation of the internal fin geometric parameters, we define the performance benefits and the preferred geometrical parameters which allow use of minimum tube material. The best axial internal fins offer less than 10 percent material savings for equal pumping power and heat duty. However, the material savings are increased to 49 percent using internal fins having a 30 deg helix angle. The heat exchanger UA may be increased 35 to 40 percent for equal pumping power and total tubing length. Pumping power reduction of 42 percent is obtained using five fins 2 mm in height with zero helix angle. The majority of the calculations are performed for water (Pr = 3) and include the effect of fin efficiency. The paper also compares the performance of internally finned and internally roughened tubes.