Precancer (carcinoma in situ) or laryngeal intraepithelial neoplasia (LIN) is a non-invasive lesion that has genetic abnormalities, loss of cellular control functions, and some phenotypic characteristics of invasive cancer and that predicts for a substantial likelihood of developing invasive cancer. Several classifications have been proposed but none has received a total agreement. With regard to diagnosis, treatment and prognosis, these lesions differ substantially from infiltrating carcinoma. Known risk factors include cigarette smoking, viral infection with subtypes of the human papilloma virus, exposure to asbestos, and probably the gastro-oesophageal reflux disease. The diagnostic work-up usually includes indirect laryngoscopy with rigid telescopes, microlaryngoscopy and biopsies for histological evaluation. Therapeutic options include wait-and-see-strategies, radiotherapy, transoral laser surgery, vocal cord stripping with cold instruments, and open partial laryngectomy. Data from the literature suggest highest local control rate with radiotherapy as initial treatment compared to other standard methods of management of dysplasia. However, transoral laser surgery can be applied repeatedly and yields excellent final results. Therefore it is now considered the treatment of choice for these lesions in the majority of patients. Local recurrences are observed more frequently than with small infiltrative carcinoma, and second primaries may arise within the upper aero-digestive tract following initial treatment. Therefore systematic follow-up is recommended for these patients.