This paper presents integration of ultrasonic and inertial approaches in indoor navigation system. Ultrasonic navigation systems allow to obtain good results whilst there are at least three beacon transmitters in the range of mobile receiver, but in many situations placement of large number of transmitters is not economically justified. In such situations navigation must be aided by other technique. This paper describes research on supporting ultrasonic system by inertial system based on Magnetic, Angular Rate and Gravity sensor. This can measure current orientation of the receiver and allows to estimate the length of the path by pedometer functionality.