The terminalN‐nitroso derivatives of L‐prolyl‐L‐alanine, L‐prolylglycine and L‐prolyl‐4‐hydroxy‐L‐proline have been synthesized and characterized. A procedure suitable for their analysis in biological samples has been developed and is based on the preparation of an aqueous extract, extraction into an organic solvent, separation by high‐performance liquid chromatography and detection by a chemiluminescence method. The average recovery in all cases was above 69% at the level of 200 μg/kg using cured meat as a food matrix; the detection limit was 10 μg/kg.