By party, the far-right Vox emerged as the third most voted force, with an estimated 53 seats - a huge leap from 24 in the last election in April.
The Socialists of acting Prime Minister Pedro Sanchez led with an estimated 122 seats in the 350-seat lower house, but further political stalemate appeared likely as votes scattered between mainstream and outlier parties. It was followed by the conservative People's Party, with 85 seats.
Center-right Ciudadanos were seen winning 10 seats while far-left Unidas Podemos fetched 26 seats.