Gut contents of 3 copepods including Oncaea venusta, O. mediterranea, and O. conifera, of the southern Taiwan Strait were picked out using a fine needle under a stereomicroscope and then examined with scanning electron microscopy (SEM). The major components of the diets of the 3 copepods were the diatoms Chaetoceros sp. and Thalassiothrix sp., although radiolarian, microzooplanktonic, and copepod debris was also found in the gut contents. The 3 copepods seemed to feed non-selectively, as the diets were determined to be diverse. The technique of examining the picked-out gut contents with SEM was developed and determined to be useful in studying the diets and feeding ecology of copepods.