Leakage of cerebrospinal fluid may occur after fracture of the skull base or after surgery on the skull base, nose, or paranasal sinuses. Further causes of cerebrospinal fluid leakage are tumours and malformations. It may also occur spontaneously. We describe four case reports illustrating diagnostic and surgical problems. Cerebrospinal fluid oto- and rhinorrhoea should be suspected in cases of recurring purulent meningitis. Immunologic demonstration of beta(2)-transferrin in secretions from the nose and ear is a diagnostic sign of cerebrospinal fluid or perilymph. Digital subtraction cisternography, CT cisternography, and flow-sensitive magnetic resonance imaging are sensitive methods for localising dural leakage. Frontal craniotomy has been the traditional surgical approach. The recent involvement of transnasal endoscopic sinus surgery and microsurgery has made it possible to treat cerebrospinal fluid oto- and rhinorrhoea with a high degree of success and less operative morbidity.