The first happened Friday evening as 24-year-old Johnny Clarke of North Augusta headed south on Duncan Road at a "high rate speed" on his Kawasaki motorcycle, Aiken County Coroner Tim Carlton said.
Clarke crossed the center line coming around a curve about 11:30 p.m. and came into the path of an oncoming pickup, Carlton said.
The head-on collision threw Clarke several hundred feet.
The pickup's driver, Barbara Davis, was taken to University Hospital with injuries that were not life-threatening, Carlton said.
About 4 p.m. Saturday, Benjamin L. Young, 27, was driving a rented Kia Spectra east on Interstate 20 in Aiken County when he drove down an embankment and hit a tree, Carlton said.
Witnesses said just prior to the wreck that Young was driving "erratically," according to the coroner.
Carlton said alcohol and drug paraphernalia were found inside the car.
Young's death was the 23rd fatal wreck in Aiken County this year.
At 6:40 p.m. Saturday in Columbia County, a two-car wreck at Wheeler Road and Tower Drive killed Kyle Loungeway, 24, of Grovetown, Chief Deputy Coroner Bonnie Holloway said.
Holloway said Loungeway was eastbound on Wheeler Road when a westbound vehicle turned in front of him.
Loungeway was trapped inside the wreckage and died, Holloway said.