There's a definite difference. Mexican is much more pronounced in flavor and aroma. I think I read somewhere that it isn't an actual oregano.

No Mexican section where they have dried chiles and spices in your supermarkets? Or, better yet, a Mexican market?

Substitute? Just regular oregano. I'm like you though -- I GOTTA have my Mexican oregano.

Click on the link and scroll down to "other plants called oregano"

Kevin

Here is a link that might be useful: Oregano

You can get Mejican oregano on the web

Here is a link that might be useful: Mejican oregano

Check if there is a latino market near you. They usually
have mexican oregano. Good stuff.

Mejican oregano is way different than Mediterranean oregano.