A man (20) was killed this morning when his van crashed in Co Roscommon.
Gardaí in Boyle are investigating the single-vehicle crash, which happened at around 9am on the N5 - the main Dublin to Westport road.
Elsewhere, two 19-year-olds and a man in his late 60s were killed in three road traffic incidents around the country over the weekend.
In Galway, Jennifer Glynn (19) from Ballintemple, Castlegar, Galway, died after she was struck by a car at 4.40am yesterday.
The incident occurred at Monivea Road, near Briar Hill in Galway. The woman, a pedestrian, was removed to Galway University Hospital but was later pronounced dead.
A male motorcyclist (19) died in Tipperary when he was involved in a single-vehicle crash some time after 3pm at Melison, Glengoole, Tipperary, on the Urlingford to Killenaule Road. Gardaí later named him as Michael Treacy from Glengoole Co Tipperary.
Gardaí in Donegal are investigating a fatal road incident that happened after 11pm on Friday in which a male pedestrian (67) died. Joseph Breslin of Meenderry, Falcarragh, Co Donegal, was struck by a car at Baile An Teampaill, Falcarragh.
Gardaí released the name of the victim of a single-vehicle road incident in Kildare that happened some time between Thursday evening and Friday morning. Jason Stone (27), of Kilglynn, Kilcock, Co Meath, died when his car hit a tree on the R407 at Painstown in Donadea, Co Kildare.
The car was discovered shortly after 11am on Friday.