More than 6,500 polling stations opened across the country at 7 a.m. and will close at 7 p.m. The first, preliminary, official results will be released at 10 p.m.
Opinion polls suggest the opposition HDZ-led Patriotic Coalition will win by a narrow margin of about five parliamentary seats, an outcome likely to entail lengthy coalition talks with smaller parties.
The conservative Coalition favors a tougher stance than its main rival, the ruling Social Democrats, on the migrant issue, seeking stricter border controls to manage the flow of people crossing Croatia on their way to western Europe.