Knox County Deputies said they responded to the intersection of Route 17 and Town House Road just before 5 p.m.
A motorcycle driven by Ronald Moon, 64, of Waldoboro hit the back of an SUV as it was pulling onto Route 17.
The passenger on the motorcycle Felicity Davidson, 63, of Rockport was not wearing a helmet and was thrown from the bike. She was pronounced dead at the scene.
Moon was taken to the Penobscot Bay Medical Center with broken bones.
The accident remains under investigation, but neither speed or alcohol are believed to be factors.
Officials said this is the sixth fatality on Knox County roads since the beginning of May.