(as) rare as hens' teeth

(as) rare as hens' teeth

Incredibly scarce or rare; extremely difficult or impossible to find. Support for the president is as rare as hens' teeth in this part of the country.
See also: rare, teeth

rare as hen's teeth

or

scarce as hen's teeth

OLD-FASHIONED
If something is as rare as hen's teeth or as scarce as hen's teeth, it is extremely rare. Record companies are becoming as rare as hen's teeth. Note: Hens do not have teeth.
See also: rare, teeth

rare (or scarce) as hen's teeth

extremely rare.
As hens do not possess teeth, the implication is that something is rare to the point of non-existence. The phrase was originally a US colloquialism, dating from the mid 19th century.
See also: rare, teeth