A small degree. of protein alignment with an external magnetic field can be obtained in a dilute aqueous liquid crystalline solution of dimyristoylphosphatidylcholine (DMPC) and dihexanoylphosphatidylcholine (DHPC). It is demonstrated that residual one-bond C-13-C-13 and C-13-H-1 dipolar couplings of methyl groups in weakly aligned human ubiquitin can be measured with high accuracy. Experimentally, the ratio between C-13-H-1 and C-13-C-13 dipolar, couplings is found to be -3.17 +/- 0.03. Assuming a static conformation of the methyl group, rapidly spinning about its 3-fold symmetry axis, this ratio corresponds to an average C-C-H bond angle of 110.9 +/- 1 degrees,which is larger than the ideal tetrahedral value of 109.5 degrees. Data indicate that the geometry of the various methyl groups is quite uniform, but that small (less than or equal to 1 degrees) deviations between the C-C vector and the axis connecting the methyl carbon to the geometric center of the three methyl protons may occur. The largest outlier is found for Ala(46), which has a positive phi backbone angle, causing its methyl group to be within van der Waals contact of the preceding carbonyl oxygen.