A shape memory alloy rod, if it is pre-twisted to create stress induced martensitic transformation, will exhibit a torsional shape memory effect, namely, some of the pre-twist will be recovered once the SMA rod is heated above its austenitic start temperature. If the pre- twisted SMA rod is constrained, a large recovery torque will be generated. Torsional shape memory alloy actuators have broad applications. This paper focuses on their applications of active helicopter rotor blade control. In this paper, we first review the effort of active rotor blade control, introduce the basic properties of shape memory alloy actuators, present the important characteristics of torsional SMA actuators governing their applications, and address issues involved in the use of torsional SMA actuators for automatic rotor blade tracking systems.