Dental anxiety is prevalent across a broad spectrum of the population. Dental phobia is extreme dental fear, which interferes with normal functioning. For any dental treatment, it is an ethical, legal and professional duty of dentists to obtain valid informed consent from their patients. The question arises as to how dental phobia impacts on patients' ability to give valid informed consent. Extreme fear may impair patient ability to understand information about the procedure, their capacity to make balanced decisions, and to make these decisions voluntarily. A trusting rapport between dentist and patient, supporting patient understanding by providing useful information material, and keeping regular appointments, may help overcome these obstacles. Other factors impacting on the informed consent process are institutional in nature. Implementing ways to overcome these is part of the dentist's duty to obtain valid consent.