We have measured the frequency of the P(27) line of (HCN)-C-12-N-14 at 1556 nm, using the 778-nm two-photon transition of Rb as a frequency reference. The measured frequency was 192, 622, 446.9 +/- 0.1 MHz. We believe that this experiment is the first absolute frequency measurement of a laser stabilized to a saturation dip at 1.5 mu m and also the most accurate measurement of a 1.5-mu m optical frequency. (C) 1995 Optical Society of America