Vallonia declivis is a species of very small air-breathing land snail, a terrestrial pulmonate gastropod mollusk in the family Valloniidae.
This species is found in Austria, France, Germany, Poland, and Switzerland. It was previously listed as part of the fauna of Slovakia, but ÃÂejka considered its occurrence in Slovakia unlikely. It lives also in the Czech Republic (in Bohemia only) and in Slovakia.