This paper attempts to investigate phonetic substances of the stress patterns of English compounds and noun phrases, showing that the theoretically derived stress structures are not consistent with the accentual patterns in real utterances. Even though it has been long claimed that compounds have the stress pattern [1 3] and that noun phrases, [2 1] as in Chomsky & Halle (1968), their difference has not been yet explored empirically or phonetically. I present a phonetic experiment conducted to see if there is any difference along the tonal contours, mostly focusing on their pitch accent distribution. 36 different compounds and 36 different noun phrases included in carrier sentences were examined, and they were varied in position within a sentence. Results showed that various accentual patterns were produced, and among them, [H* X] predominantly occurs in all three positions in both compounds and noun phrases, whereas the patterns [X H*] and [X X] appear relatively more frequently in final position than in initial and medial position. Furthermore, the pattern [Ac + No], in which the preceding element is pitch-accented with no accent on the following one, is the major stress pattern in both compounds and noun phrases and in all three sentence positions. This suggests that there seems to be no difference in accentual patterns between compounds and noun phrases, which is not consistent with the hypothesis. The results are interpreted as saying that the preceding element alone tends to be prominent with no accent following it both in compounds and noun phrases, and that therefore, theoretically speculated phonological claims are not always phonetically supported.