The event pooled more than 500 participants from Croatia and abroad.
Kosor, who is also the Minister of Family Affairs, War Veterans and Inter-generation Solidarity, said that 237 persons, mostly aged between 20 and 30, had died of drug addition in the past three years.
Kosor said that the government and its commission for the prevention of drug abuse had launched various efforts to prompt state and local institutions to implement an action plan for the fight against drug abuse.
There are 18,476 registered addicts in Croatia, Kosor said, adding that the actual number was much higher.
The situation is the most critical in Zagreb and the counties of Split and Primorje-Gorski Kotar, she said.
The Pula conference, to last until Wednesday, is held to mark the year 2004 as the international year of the family and the year of the fight against drug abuse in Croatia.