We suggest that high‐efficiency frequency upconversion and downconversion can be achieved by four‐wave mixing in media containing infrared‐active molecules. The high‐efficiency results from the relatively large vibrational matrix elements and small energy denominators. Numerical calculations are presented for generation of radiation at 2&ohgr;1+&ohgr;2in HCl where 2&ohgr;1is tuned to an electric‐dipole‐forbidden vibration‐rotation transition. We also present some general considerations for four‐wave mixing in molecular media.