The notion of intonation units is very basic to the study of discourse. Nevertheless, a clear-cut definition of what comprises an intonation unit has not been forthcoming. In reality, it seems that the boundaries delineating intonation units are somewhat easier to define, though this is by no means a closed subject. In this preliminary study of spoken Israeli Hebrew, we took four common criteria for intonation unit boundaries (fast initial speech, slow terminating speech, pitch reset, pauses) and analyzed their occurrences in a segment taken from a spontaneous speech corpus, containing approximately 54 such units. This segment was parsed perceptually by four researchers, and the resultant boundaries were analyzed acoustically to determine which were present at each boundary. A number of interesting conclusions result: only a quarter of the boundaries conformed to all cues, while two boundaries that were agreed upon by all the listeners conformed to none. Final lengthening was most prevalent, followed by pitch reset, then pauses, and finally fast initial speech. A larger study, involving many more units and more speakers is in progress.