四吡咯（Tetrapyrroles）是一类化合物，除了其中的咕啉（corrin）之外，该种类化合物的其它物种含有4个吡咯，且这4个吡咯是经由单碳（如亚甲基或次甲基）桥进行链接，可分为线性或环状两大类。 而咕啉也含有四个吡咯环，但仅有三个单碳桥，结构可参见维他命B12。

线性四吡咯含有3个单碳桥，包括：

环状四吡咯含有4个单碳桥，包括：

Tetrapyrroles are a class of chemical compounds whose molecules contain four pyrrole rings held together by direct covalent bonds or by one-carbon bridges (=(CH)- or -CH
2- units), in either a linear or a cyclic fashion. A pyrrole ring in a molecule is a five-atom ring where four of the ring atoms are carbon and one is nitrogen. In cyclic tetrapyrroles, lone electron pairs on nitrogen atoms facing the center of the macrocycle ring can bond or chelate with a metal ion such as iron,cobalt, or magnesium.