The defending champion in the singles was local hero Marin Čilić , who did not compete this year. David Marrero and Fernando Verdasco won the doubles title last year. While Marrero played alongside Martin Kližan this year and was able to defend the title, Verdasco did not take part in the tournament.
The field of participants in the single competition consisted of 28 players, that of the doubles competition consisted of 16 pairs. The four top seeded players in the singles each received a bye to the second round.
The qualification for the ATP Vegeta Croatia Open 2013 took place from July 20-22, 2013. Four qualifying places were played that entitle them to participate in the main draw of the tournament.
At the ATP Vegeta Croatia Open 2013 the following prize money and world ranking points were paid out or credited for reaching the respective round. Players who entered the main field from qualification have received the specified qualification points in addition to those for reaching the respective round. Otherwise the amounts are not to be understood as cumulative. The amounts for the double competition apply per team.