Analysis of all of the PI cycle phospholipids is usually performed by twodimensional thin-layer chromatography. A simple and rapid method for analyzing the phosphoinositides by one-dimensional thinlayer chromatography has been developed.The non-polyphosphoinositides in cells were first extracted with chloroform: methanol:water (8: 4: 3), and then the polyphosphoinositides were extracted with chloroform:methanol: water: concentrated HCI (100:100: 50: 1). Each part of phospholipids were further separated by one-dimensional thin-layer chromatography with different developing systems，i. e.，chloroform，methanol，acetic acid:formic acid:water(70:30:12:4:2) for non-polyphosphoinositide phos-pholipids and chloroform:methanol:water: NH₄OH(40:48:10:5) for polyphospho-inositides. The method can be used for comparative analysis of phosphoinositides in small samples，and also for the extraction，separation and quantitation of polyphospho- inositides. separation and quantitation of polyphosphoinositides in samples which are not labelled with isotope.