The 1,3-dipolar cycloaddition of 4-chlorobenzonitrile oxide to the unsaturated system of (À)-(R)-carvone occurred exclusively at C(8) to give a new isoxazoline derivative. This derivative reacts with NH 2 OH to yield a new heterocycle, observed for the first time. On the other hand, the addition of 4-chlorobenzonitrile oxide to the unsaturated lactone (À)-4aa,7a,7ab-nepetalactone gave, in a good yield, also a new heterocycle, again obtained for the first time. The terpenoid (À)-(R)-carvone and iridoid (À)-4aa,7a,7ab-nepetalactone were isolated from Moroccan species Mentha viridis (L.) and Nepeta tuberosa (L.), respectively. The new heterocycles obtained were identified by combination of chromatographic and spectroscopic methods.