The magnetic field-induced modification of the electric-dipole forbidden transitions between the lowest rotational states of the 2 Π 1/2 and the 2 Π 3/2 substates of a 2 Π diatomic radical is probed by model calculations for the ground electronic states of NO, OH and CH. Magnetic fields in the range of 0−12 T and more were considered and the intensities of the respective allowed rotational transitions for the given systems were calculated for comparison. In particular, NO shows enhanced field dependence of calculated intensities.