Hoisin sauce, or Haixian Sauce, is a Chinese dipping sauce.

Despite the literal meaning of "seafood," Hoisin sauce does not actually contain fish. It is similar to the sweet noodle sauce made from fermented soybeans, but has the added ingredients of garlic, vinegar, and chilli peppers. Additionally, it tastes less pungent than sweet noodle sauce.

Mandarin-style Hoisin sauce ingredients include water, sugar, soybeans, white distilled vinegar, rice, salt, wheat flour, garlic, and red chili peppers, and several preservatives and coloring agents.

Traditionally, Hoisin sauce is made using sweet potato.