European Union officials are concerned about the state of Turkey's democracy, and have voiced their worries about the independence of the courts and media, the BBC reported.
The talks are held being held following a recent purge of Turkish police officers and prosecutors, who have been arrested for corruption.
The Turkish government is frustrated with the slow pace of the talks.
The negotiations resumed in November after they were suspended for nearly 3 1/2 years.
The talks initially began in 2005.
Some member countries, including Germany and France, are concerned about Turkey joining the European Union due to its location and size, which could change the nature of the EU.
Erdogan hasn't been in Brussels in five years, and he is set to meet with European Council President Heram Van Rompuy and EU Commission President Jose Manuel Barroso.