The infrared spectra of all the deuterated methanes of high isotopic purity have been obtained with prism resolution and 27 of the 29 fundamentals were observed. The frequencies observed have been compared with the previous grating and prism data and 'best' values of the fundamentals have been suggested. The present data are considered to give more reliable frequencies for most of the fundamentals of CH3D, CH2D2, and CD3H than were previously available.