Academician Alica Wertheimer Baletic said Croatia had been faced with steady depopulation, including a negative birth rate and a negative migration balance for 20 years.
She also warned about negative demographic determinants for the labour force.
Since 1971, the portion of young citizens has been decreasing.
Since 1991, youth and working-age population has been falling with a rapid rise in the number of senior citizens.
Wertheimer Baletic said the Croatian authorities had to take into account the age structure of the population and pursue polices to correct imbalances.
Labour Minister Mirando Mrsic said Croatians would be living longer thanks to medicine and they would also work longer.
The president of the Croatian Academy of Sciences and Arts, Zvonko Kusic, said 60 years ago, the cohort of children under 15 was 27%, and the cohort of people older than 65 was 6%. Currently, children under 15 account for 15% of the total population, while those above 65 years of age account for 17%.
"We now have an inversive pyramid and it is estimated that in 2030, every fourth Croatian will be older than 65," Kusic said.