蓝奶酪又称蓝纹干酪、蓝芝士、蓝起司，是干酪的一种，特点是以青霉菌发酵而成，使其表面有一些蓝色的斑纹。蓝干酪可以用牛奶或羊奶制成。较著名的蓝干酪种类包括法国出产的布勒·德·奥福格芝士以及罗克福干酪，还有意大利出产的古冈左拉芝士。

蓝干酪因为青霉菌发酵的作用，味道偏咸，除了单独食用外，也常用于烹饪，为酱汁等的佐料。

Blue cheese is a general classification of cheeses that have had cultures of the mold Penicillium added so that the final product is spotted or veined throughout with blue, or blue-grey mold and carries a distinct smell, either from that or various specially cultivated bacteria. Some blue cheeses are injected with spores before the curds form, and others have spores mixed in with the curds after they form. Blue cheeses are typically aged in a temperature-controlled environment such as a cave. Blue cheese can be eaten by itself or can be spread, crumbled or melted into or over foods.