A 25-year-old woman is recovering in hospital following a serious assault in the Lucan area overnight and in an unrelated incident police in Cavan are also investigating an alleged sexual assault on a 16-year-old girl in Ballyjamesduff.
The woman was walking on the M4 near the Spa Hotel when she was dragged into hedge by a man and attacked.
She was badly beaten in the assault and sustained serious facial injuries.
A passer-by saw the altercation, alerted gardai and called for help.
The woman was brought to Dubin's Mater hospital. Gardai have yet to establish a motive for the attack.
Meanwhile, gardai in Cavan are investigating an alleged sexual assault on a 16-year-old girl in Ballyjamesduff, Co Cavan last night.
The alarm was raised when the girl approached a police patrol car in the Crosskeys area of Ballyjamesduff shortly after midnight and told them of the attack.
She was admitted to Cavan General Hospital before being transferred to the sexual assault unit of the Rotunda Hospital in Dublin, a garda spokesman said.
A motor car was been impounded and some evidence recovered as part of the police investigation.
And in Dundalk, Gardai are continuing to investigate an alleged sexual assault on a woman in the town in the early hours of yesterday morning.