With the development of the Millipore filter, meningeal metastases are being identified more frequently as a complication of many types of carcinoma, including breast, lung, pancreas, stomach, and prostate. Regardless of the primary source, adenocarcinoma cells appear to have a propensity to metastasize to this site. In recent years, carcinomatous meningitis has been reported very infrequently in gastrointestinal malignancies, as compared with other primary sites. We present two cases of carcinomatous meningitis, one in a 29-year-old man with adenocarcinoma of the colon and another in a 51-year-old man with gastric carcinoma. Survival after this complication is presently poor, but treatment may offer amelioration of disabling symptoms. The aggressive nature of these metastases emphasizes the need for early clinical suspicion and examination of spinal fluid in patients with gastrointestinal malignancies.