We offer an approximate method with which to calculate proton N.M.R. spectra generally caused by dipole-dipole interactions. The method consists of subdividing the spin system of the liquid crystal molecule into interacting blocks. The spectrum of each block is calculated exactly. The interaction between spins of different blocks is calculated approximately. The method is compared with the known methods using 4-n-pentyl-d₁₁-4′-cyanobiphenyl (5CB-d₁₁) and 4,4′-dimeth-oxyazoxybenzene (PAA) as examples.