Objectives: The purpose of the present study was to review the epidemiological aspects of tendon ruptures of the knee extensor apparatus at a level 1 hospital. Methods: We retrospectively analyzed 76 lesions of the knee extensor apparatus that were treated surgically at the Miguel Couto Municipal Hospital between March 2004 and March 2011. We took into consideration age, sex, trauma mechanism, anatomical classification of the lesion, affected side, comorbidities and associated lesions. Results: Among the patients studied, 68 were male and the mean age was 36 years. Regarding the trauma mechanism, 62 lesions occurred due to direct trauma; the right side was affected in 21 cases; eight presented comorbidities and four presented associated lesions. Conclusion: The majority of the patients were male, at an economically active age (young people), and were victims of direct trauma. Ruptures of the patellar ligament were the most frequent lesions. Associated lesions were rare and comorbidities were infrequent in our sample.