Cellophane noodles (also known as Chinese vermicelli, bean threads, bean thread noodles, crystal noodles, or glass noodles) are a type of transparent noodle made from starch (such as mung bean starch, yam, potato starch, cassava or canna starch), and water.

They are generally sold in dried form, boiled to reconstitute, then used in soups, stir fried dishes, or spring rolls. They are called "cellophane noodles" or "glass noodles" because of their appearance when cooked, resembling cellophane, a clear material or a translucent light gray or brownish-gray color.

Cellophane noodles are generally round, and are available in various thicknesses. Wide, flat cellophane noodle sheets called mung bean sheets are also produced in China.

Cellophane noodles should not be confused with rice vermicelli, which are made from rice and are white in color rather than clear (after cooking in water).

In Chinese, the most commonly used names are:

They are also marketed under the name saifun, the Cantonese pronunciation of the Mandarin xì fěn (Chinese: 細粉; literally "slender powder"), though the name fan2 si1 (粉絲) is the term most often used in Cantonese. While by itself the character fěn (Chinese: 粉) means powder, it etymology is probably related to diàn fěn (simplified Chinese: 淀粉; traditional Chinese: 澱粉), which means "starch" — the substance from which the noodles are made.