This paper describes the design, analysis, and experimental results of an Attitude and Heading System based on total state (direct) Extended Kalman Filtering technique. The presented scheme is suitable for implementation using low cost sensors. Attitude determination systems are essential for real time vehicle navigation, guidance and control applications. When low cost sensors are used, efficient and robust algorithms become necessary for an acceptable performance. For the proposed approach, a low cost Inertial Measurement Unit (IMU), formed by 3-axis gyroscope, 3-axis accelerometer, and 3-axis magnetometer, provides the input measurements. A Kalman Filter, in direct configuration, estimates the state of the system, which is formed by a quaternion, representing the body 3D orientation, and the biases of gyros. Experimental results with real data show that the proposed algorithm is able to maintain an accurate and drift-free attitude and heading estimation.