This paper reports on an instrumental study of Greek yes-no question intonation. The study was based on readings (by seven speakers) of controlled speech materials, and confirmed the validity of the initial autosegmental analysis of the Greek yes-no question melody as L* H-L%. The study presents a wide range of data regarding the scaling and alignment of all tonal targets in a variety of conditions, which show the effects of tonal crowding on the realisation of the targets. Further, it provides empirical evidence that the alignment of the H-phrase accent depends on the location of the L* nuclear accent, which shows the secondary association of phrase accents.