Aim: To estimate the incidence of intracranial tumors in the adult population of the Varazdin County, Croatia, for the 1996-2004 period. - - - - - Methods: Setting: Varazdin County General Hospital and four university hospitals in Zagreb, the capital of Croatia. Study period: January 1, 1996 to December 31, 2004. Incident patients: county residents admitted for newly diagnosed intracranial tumors according to the WHO diagnostic criteria. Demographic data were extracted from the 2001 Croatian census. Incidence rates (IRs) per 100,000 person-years (p-y) and annual IRs (per 100,000 persons) were determined and compared as incidence rate ratios (IRRs) with 95% CI. - - - - - Results: For primary intracranial tumors (PITs), IR was 12.1/100,000 p-y (95% CI: 10.3-14.2), comparable in men and women. The highest incidence was recorded for glioblastoma (IR 4.8, 3.7-6.2) and meningioma (IR 3.1, 2.2-4.2). The incidence of PIT was somewhat greater than that of metastatic tumors (IRR 1.58, 95% CI: 1.22-2.05, P < 0.001). Metastatic tumors were more frequent in men than in women, especially metastatic lung tumors (IRR 6.08, 2.32-20.16, P < 0.001). IRs of all PIT taken together, neuroepithelial tumors cumulatively, nonepithelial tumors cumulatively, glioblastoma and meningioma were higher in the population aged >= 40 vs. population aged <= 39 (all IRRs with 95% CI greater than 1, P < 0.05 or < 0.001), comparable in men and women. Women were somewhat older than men at the time of diagnosis of PIT: median difference -6 years (95.1% CI: -10 to -1, P < 0.05). Annual IRs for all these tumor categories showed increasing trends over the study period. - - - - - Conclusion: Overall, there was an increasing trend in the incidence of primary intracranial tumors in the Varazdin County. Data did not allow estimation for most of the specific tumor types.