<正> The lamellar structure of a thermotropic aromatic polyester with flexible spacer has beenstudied by using transmission electron microscopy. It was found that the lamellar structure couldbe observed in the crystalline samples of this semirigid polymer crystallized from different states.The thickness of lamellae is around 10 nm, which is similar to that of the conventional polymersof flexible chain molecules. The molecular chains in the lamellae are oriented in the thicknessdirection as determined by electron diffraction. The possibility of molecular chains folding in the lamellae has been discussed.