A comparative analysis of population development on the islands of Krk, Cres and Lošinj emphasizes the changes in the number and distribution of population from the first official census in 1857 to this day, with a special review of those who were intensified at the turn of the century. The island of Krk, in comparison with other islands, has the most favorable total development of the population for now, because he is the only one with a total increase, especially thanks to the transport connections with the mainland (from 1980) and the development of tourism. But, despite this fact, he has a natural decrease, like the islands of Cres and Lošinj. Therefore, migrational component has a very significant impact on the future population density of these areas, but neither immigration does not mean that the average age of population would be lower today as it would be in the past, so the deceleration of ageing is not noticed. That process is registered in the local population by the end of the 20th century and many demographic indicators do not show an improvement of demographic trends in the next decade. So, a more detailed insight into the demographic sphere of this area enables us to understand the complexity, particularly modern, changes in the tendencies of population development on the islands of Krk, Cres and Lošinj.