One of the most common misperceptions about gifted students is that they will be successful with the normal curriculum offered in schools. Most people assume that those intellectually gifted students succeed in all subjects, have high scores in tests and that will guarantee a bright future. In fact, a number of gifted students at the school system were not performing at a level commensurate with their abilities, and even a great many of of them show underachievement character traits. Regarding the literature in this field, studies have shown that from 9% to 50% of these students are performing below their ability levels. Very recently, the topic of gifted underachievement and how to reverse it has received a great deal of attention in the gifted education literature. Educators commonly identify most of the gifted student underachievers as reluctant, lazy, unmotivated, or the ones as having behaviour problems (Seeley, 2004). The main objective of this study to add to the knowledge base on this issue to educators, counsellors and parents by investigating the occurrence of underachievement behaviours and their determining factors in a population of gifted students.