The aim of the study was the comparison of intellectually gifted secondary grammar school students with students from the average population of secondary grammar school students, in the level of overexcitability and prediction of intellectual giftedness through the various types of overexcitability. The research sample consisted of 88 secondary grammar school students aged 16-17 years. The target group, who were identified as intellectually gifted students, consisted of 44 students, whereas the control group consisted of 44 students from an average population of secondary grammar school students. We used tests of intellectual ability, Raven's Advanced Progressive Matrices Test, Intelligence Structure Analysis, and Urban's Figural Test of Creative Thinking to identify intellectually gifted secondary grammar school students. Types of overexcitability were assessed by means of the Overexcitability Questionnaire. Statistical analysis showed significant differences in the level of overexcitabilities between intellectually gifted secondary grammar school students and students from the average population of secondary grammar school students. Significant predictive power of intellectual and emotional overexcitability was found in relation to intellectual giftedness.