BACKGROUND: The incidence of type 1 diabetes mellitus (T1DM) among children and adolescents increased during the last 50 yr. The T1DM incidence in Croatia was 8.87/100.000/yr over 1995-2003, with an annual increase of 9%, which placed Croatia among countries with moderate risk for T1DM. AIM: To investigate incidence rates and trends of T1DM from 2004 to 2012 in 0 to 14-yr-old Croatian children, and to compare the results with previous studies in Croatia and other European countries. METHODS: T1DM crude incidence rates are estimated for the entire group and three subgroups: 0-4, 5-9, and 10-14 yr. Standardized incidence is calculated using the method of direct standardization according to World Health Organization (WHO) standard world population. The incidence rates by gender, age groups, seasonality, and calendar year, and their interactions were analyzed using Poisson regression model. RESULTS: A total of 1066 cases were ascertained over 2004-2012. The standardized incidence was 17.23/100.000/yr (95% CI: 16.19-18.26), with no significant differences in incidence rates or trends between boys and girls. Statistically significant annual increase of 5.87% (p < 0.001) was found for the whole group, and for the subgroups 5-9 yr (6.82%; p < 0.001) and 10-14 yr (7.47%; p < 0.001). In the youngest subgroup (0-4 yr), annual increase was lower (2.43%; p = 0338) and not statistically significant. CONCLUSION: The incidence of childhood T1DM is increasing in Croatia, thus placing Croatia among countries with high risk for T1DM. The annual increment of 5.87% is considerably lower than 9.0% reported earlier, but still higher than the European average (3.9%). The increase in incidence ceased in youngest children.