The aim of the present study was to clarify the interaction between ethylene and abscisic acid (ABA) and maturation in highbush blueberry. We investigated the berry quality, ethylene evolution, and ABA concentration of berries treated with ethephon, an ethylene-generating compound; aminoethoxyvinylglycine (AVG), an ethylene synthesis inhibitor; ABA; and nordihydroguaiaretic acid (NDGA), an ABA synthesis inhibitor, before the onset of maturation in the highbush blueberry ‘Jersey’. The harvest time and the increasing time of ethylene evolution and ABA concentration in berries were earlier in 200 mg·L⁻¹ ethephon treatment than in the control. Treatment of 30 mg·L⁻¹ ABA progressed the time of increased ABA concentration but had little effect on the harvest time or ethylene evolution. AVG treatment at 150 mg·L⁻¹ delayed the harvest time accompanied by decreasing the peak value of ethylene evolution and delaying the time of increased ABA concentration. Treatment of 300 mg·L⁻¹ NDGA decreased the peak value of the ABA concentration, while it did not affect the harvesting time or ethylene evolution. These results suggest that ethylene, not ABA, induced maturation of blueberry at the mature green stage, and that ethylene was more closely involved than ABA with the progress of the whole maturation process.