It is well documented that the cricothyroid (CT) space opens and closes with changes in pitch, narrowing with rising pitch and widening with falling pitch. Indeed, cricothyroid approximation surgery, a procedure where the CT space is deliberately made smaller, is used in male to female transgender subjects to successfully elevate vocal pitch. The present study focuses on investigating the relationship between the anterior CT space at rest and vocal range in female singers. Laryngeal dimensions (anterior CT space and heights of the thyroid and cricoid cartilages) were measured using ultrasound in 43 healthy, classically trained, female singers. Potential associations with and between age, ethnicity, anthropometric indices (height, weight, body mass index), neck dimensions (circumference and length), vocal data (practice and performance vocal range, lowest and highest practice and performance notes) along with usual speaking fundamental frequency were also explored. The main finding was that mezzo-sopranos have a significantly wider resting CT space than sopranos (11.6 mm versus 10.4 mm; P=0.007). Mezzo-sopranos also had significantly lower ‘lowest and highest’ performance notes and speaking fundamental frequencies than sopranos. Furthermore, there was a weak but significant negative correlation between the magnitude of the anterior CT space and the lowest performance note (r=-0.448; P=0.003) but there was no significant correlation with either the highest performance note or vocal range. These results suggest there is a relationship between the CT space and the lowest note a female can sing. This was evident in the correlation of a small CT space with a higher ‘lowest performance note’. It appears that the CT space influences how low female singers can sing, but not how high they can sing.