Dear students, the textbook Otorhinolaryngology I is written by the author from Jessenius Faculty of Medicine Comenius University in Martin who has been teaching otorhinolaryngology for decades. He has translated his experiences into the study materials in order to facilitate, and perhaps make the study of this medical field interesting. This first part of the book consists of chapters that cover area of nose and paranasal sinuses, oral cavity, pharynx, and larynx. Emphasis is placed on practical information that can be used not only by undergraduate students when studying otorhinolaryngology but also later in their clinical practice. Many of the conditions described here can be encountered even by primary care physicians for adults and children. The most common are inflammations of the upper airways, but also tumors or suffocation. We believe that the text may be of help to general medicine and dental students to understand the etiology, symptoms, diagnosis, including ENT screening methods, differential diagnosis, treatment and prognosis of ENT diseases.