When the mouth is affected by cancer, difficulties in satisfying basic human needs such as eating, tasting, swallowing, and speaking might arise, and the existential significance of the mouth might become obvious. How does it feel to live with these difficulties? What does it mean to be a human being living with the consequences of oral cancer? Five patients with oral cancer were interviewed a median time of 4 years after the beginning of treatment. A hermeneutic research approach was used to understand, explain, and interpret the transcribed interviews and showed how the consequences of oral cancer affected the being-in-the-world of the participants in three ways: existing as oneself, existing in the eyes of others, and existing with others. Against the background of the philosophy of Martin Heidegger, these findings illuminate how essential the mouth is to a human being's identity and existence.