The microwave spectrum of methyl phosphonic difluoride, CH 3POF 2, was reinvestigated in the region of 26 500 to 36 000 MHz. Rigid rotor rotational constants (MHz) for the ground state were obtained from an improved data base and are A = 4495.814(7), B = 4271.851(5), and C = 4125.89(5). Previous microwave assignments of two vibrational satellites are shown to be erroneous. Three sets of excited vibrational state lines have been identified and fit well to rigid rotor theory. Relative intensity measurements permit tentative vibrational assignments of the states to first excitations of the CH 3 torsion, CPO bend, and PF 2 deformation by comparison to vibrational work. The three excited states exhibited no resolvable microwave transition splitting. The methyl torsional barrier is estimated to be 3.5 kcal/mol from the previously assigned v = 1 ← 0 torsional mode and the internal rotational parameter, F, which was calculated earlier from the structure.