Abstract: During 2011, 2012 and 2013 samples of olive leaves were collected from olive growing areas in Croatia to establish an assessment of peacock olive leaf spot – Spilocaea oleagina. Collected samples were used to establish latent infection of olive leaves with the fungus. The latent infection is detected using the leaves soaked in 5% sodium hydroxide. Samples were collected from the most common variety Oblica and other varieties – Istarska bjelica, Buza, Carbonaca, Krvavica, Drobnica, Lastovka, Starovjerka, Plominka, Šimjaca, Drobnica and Paska. The results showed differences in susceptibility of cultivars and even within the same locality. Fixed percentages of infections ranged from 0% to 100% infection. Our results indicate that the majority of olive growers have not implemented to date the protection against pathogens of peacock olive leaf spot. The results show the prognostic significance of conducting activities related to monitoring the disease and the need to provide regular forecasts on the protection of olive trees against this disease.