Introduction Premalignant lesions are considered both a hyperplastic and dysplastic stage of epithelial lesions in the glottic larynx that may or may not progress into an invasive carcinoma. The evolution of laryngoscopic procedures in outpatients has provided better access to important information for safe and easy diagnosis of laryngeal pathologies. Objective The goal of this study was to determine the accuracy of the preoperative exam for diagnosis of premalignant laryngeal lesions and their connection with benign diseases of the vocal folds, as well as to assess their epidemiologic characteristics. Methods This is a retrospective and longitudinal cohort study performed through the review of surgical records of patients who underwent laryngeal microsurgery performed by a single surgeon from 1990 to 2009. Results Preoperative assessment of outpatients was 64.4% accurate. Vocal fold cysts were the most frequently associated benign lesions. The patients who apparently had premalignant lesions represented 10.57% of those who underwent laryngeal microsurgery. Premalignant lesions prevailed in men (69.49%) age from 41 to 50 years (32.20%). Conclusion Although the evolution of laryngoscopic procedures in outpatients has provided better access to important information for safe and easy diagnosis of laryngeal pathologies, about one-third of premalignant lesions are diagnosed just during the laryngeal microsurgery. Cysts were the most prevalent concomitant benign lesion of the vocal folds. Males were more prevalent than females and the predominant age bracket was between 41 and 50 years.