This work describes ion temperature measurements made by means of Doppler line broadening in a rotating magnetic field pinch experiment. A 12-channel Fabry-Perot interferometer has been constructed and profiles of various helium and impurity lines were measured as functions of time and position in the discharge tube. The theoretical standard deviation of the results was computed by a statistical analysis using a Monte-Carlo simulation programme. This allowed us to separate the real variations of the plasma from the fluctuations of the measurements. The main limitations of the accuracy of the results were due to lack. of light intensity and parasitic broadening mechanisms (Stark and reabsorption effects). Nevertheless, reasonable values of the temperatures of ionised nitrogen, oxygen and helium were obtained for three different filling pressures (20, 60 and 180 mTorr He).