Once thought to be rare, leptomeningeal carcinomatosis from systemic cancer is becoming more common as cancer patients are living longer. Lung, breast and malignant melanoma comprise the majority of solid tumor cases with this condition. The hallmark of the disease and the differential diagnosis are discussed. Only the identification of malignant cells in the cerebrospinal fluid provides as clear-cut diagnosis. Biochemical markers, thus far, cannot substitute for a positive cytology, but may aid in the diagnosis. We report and discuss 3 cases of complete biochemical and radiological assessment and variable degree of aggressiveness of treatment. Better control of the systemic cancer may result in prolongation of life.