26-year-old Slovakia midfielder Hamsik has been a key part of the Napoli side since joining in 2007.
Naples, Italy: Napoli president Aurelio De Laurentiis says midfielder Marek Hamsik has extended his contract with the Serie A club until 2018.
Aurelio De Laurentiis announced the agreement on Twitter, shortly after Napoli's 2-1 victory over Benfica in a friendly, and says "it is a perfect marriage".
The Napoli chief also posted a picture on the social media site of himself and Hamsik drinking a glass of champagne, with the caption "Marek and I drinking to the new deal".
Hamsik has been a key part of the Napoli side since joining in 2007. The 26-year-old midfielder has more than 60 caps for Slovakia.