The sternocleidomastoid muscle is important anatomically and clinically because of its relationship with many neurovascular structures in the neck. The muscle descends obliquely across the side of the neck and divides it into anterior and posterior triangles. In this case report, the additional clavicular head of bilateral sternocleidomastoid muscle was shown. During routine dissections of the neck for anatomy education in the Department of Anatomy Laboratory in the Faculty of Medicine at the Gazi University, additional clavicular heads of sternocleidomastoid muscle were observed bilaterally. The additional clavicular heads originated from the superior surface of the middle third of the clavicle. Furthermore, on the left side of the neck, muscle fibers originating from sternal head of sternocleidomastoid muscle and blending with clavicular head of sternocleidomastoid muscle were seen. Both of the minor supraclavicular triangles were narrower than normal. Unusual clinical cases in medical area makes diagnosis and treatment more difficult. Knowledge of anatomical variations is very important for avoiding of this difficulty.