Andrew McGinley is suing the HSE, St Patrick's Hospital in Dublin and a consultant psychiatrist over the care of his wife.
Deirdre Morley killed their three children in Co Dublin two years ago, but was found not guilty of their murder by reason of insanity.
Mr McGinley lodged the High Court action on Wednesday - the same day as his wife lodged a similar lawsuit.
He says he's asked for a review into his wife's case but is still waiting.
"What I don't understand yet is why my children died... I just want to know why."
The grieving father said he considers his family's story "the worst case scenario" for a family effected by mental illness.
"If you can't learn lesson from our tragedy, I don't think lessons will ever be learned."
Andrew McGinley says he wants mistakes made in his wife's care to be reviewed and used to prevent further tragedies.
