The present study aimed to: (i) estimate the prevalence of self-reported high fear of intra-oral injections, high blood-injury fear, and injection fear; (ii) explore the overlap between high fear of intra-oral injections and high fear of dental treatment; and (iii) evaluate the possible consequence of high fear of intra-oral injections in terms of avoidance of dental care. The sample included 1,441 subjects, 10- to 16-yr of age, attending elementary schools in a county of Norway. Data were collected using questionnaires that were completed in classrooms. The survey instruments used were the Intra-Oral Injection Fear-scale, the Children's Fear Survey Schedule-Dental Subscale, the Injection Phobia scale for children, and the Mutilation Questionnaire for children. In total, 13.9% of the children reported high intra-oral injection fear. A strong association was found between fear of intra-oral injections and dental fear. When an intra-oral injection was needed, 10.6% would avoid dental treatment. In multiple regression analysis, high intra-oral injection fear was found to be associated with avoidance of dental treatment (OR = 6.52; 95% CI: 3.99–10.67). It was concluded that high fear of intra-oral injections was prevalent and might lead to avoidance of necessary dental treatment. Hence, intra-oral injection fear should be addressed before treatment of dental fear.