The menisci consist of fibrocartilage and are an important supporting structure of the knee joint. They are poorly vascularized and have to withstand a high mechanical strain and load; therefore, lesions are common, especially on the medial side. Meniscal lesions are among the most frequent surgical procedures in orthopedic surgery. Meniscal lesions are diagnosed by a careful clinical examination in 80% of all cases in spite of modern imaging techniques such as magnetic resonance imaging (MRI). In the last 15 years, arthroscopic meniscectomy has become the 'golden standard' of therapy. Arthroscopy provides a powerful tool to precisely locate and classify the type of meniscus injury and to perform arthroscopic meniscectomy at the same time. This means less morbidity, reduced hospitalization time and earlier return to work and hence reduced costs. The endoscopic technique allows to exactly remove the damaged parts of the meniscus with precision instruments (partial meniscectomy). Former open techniques only allowed the complete removal of the meniscus. The arthroscopic techniques used nowadays allow a preservation of the functionally important edge of the meniscus, which is responsible for the stability and the biomechanics of the knee joint and can thus prevent an early onset of arthrosis. In rare cases of peripheral meniscal tears in young patients, arthroscopic refixation is an advantageous treatment option. Partial arthroscopic meniscectomy and arthroscopic meniscus refixation are challenging therapeutic procedures that require a trained and experienced orthopedic surgeon. Today diagnostic arthroscopy is more and more abandoned in favour of noninvasive and reliable MRI techniques. MRI is also useful in cases of previous knee surgery and clinically unclear findings, but should not be used on a routine basis. In differential diagnosis, the orthopedic surgeon always has to evaluate the MRI findings as to their impact. Today, arthroscopic knee surgery is a reliable, technically sophisticated and standardized technique to treat meniscal damages of all patients. There is a relatively low rate of complications, provided that the indication for the procedure is critically applied and restricted to patients with sufficient clinical and MRI findings.