Poland's conservative Law and Justice (PiS) party led by eurosceptic Jaroslaw Kaczynski has won an absolute majority in general elections, public broadcaster TVP projected, a victory ending eight years of centrist rule.
An exit poll after Sunday's vote suggested the PiS picked up 242 out of 460 seats in the lower house of parliament, ousting the governing Civic Platform (PO) liberals who had 133 seats.
Kaczynski declared victory, and his first step was to pay tribute to his twin bother, the late president Lech Kaczynski, who died in a 2010 jet crash in Smolensk, western Russia.
"Without him, we wouldn't be here today. His spirit is stronger than his body. We must keep his memory alive," Kaczynski said, also recalling scores of Polish statesmen who perished in the crash.
"This is the first time in the history of Polish democracy that a single party has scored a majority," he added.
Prime Minister Ewa Kopacz conceded defeat, the AFP news agency reported.
"We didn't waste the last eight years," told PO members at her campaign headquarters in Warsaw.
"Poland is a country that has made economic progress, unemployment is down to single-digits. This is the Poland we leave to the election winners."
Kaczynski's push for power preyed on fears arising from Europe's worst refugee crisis since World War II and analysts said a PiS government was likely to reverse Kopacz's decision to accept refugees under an EU quota plan.
Kaczynski claimed refugees were bringing "cholera to the Greek islands, dysentery to Vienna, various types of parasites," in comments that critics said recalled the Nazi era.
He insists Warsaw should financially support EU efforts to tackle the crisis, but not take in refugees - a view surveys suggest is shared by nearly 60 percent of Poles.
Leftist parties were voted out of parliament for the first time since the the advent of democracy after the collapse of communism in 1989.