The rotational spectrum of the NaC radical in the v=0 level of its X (4)Sigma(-) state has been recorded using millimeter/submillimeter-wave absorption spectroscopy. This work is the first spectroscopic observation of this species. The molecule was generated under dc discharge conditions by the reaction of sodium vapor with methane; the vapor was generated in a Broida oven. Thirteen rotational transitions were measured in the frequency range from 231 (N=9<--8) to 539 GHz (N=21<--20). The quartet fine structure was partially resolved for each transition. The rotational transition frequencies were modeled with an effective Hamiltonian. An ambiguity in the fitting procedure produced two alternative values of the spin-spin coupling constant lambda, one large and the other small in magnitude. A simple theoretical estimate of this parameter, based on atomic orbitals on the C- atom, suggests that the latter fit is the correct solution to the problem. The same ambiguity occurs in the fit of the rotational spectrum of KC in its X (4)Sigma(-) state published earlier [Xin and Ziurys, J. Chem. Phys. 110, 4797 (1999)]. The revised, preferred fit of the data is given in this paper.