Alphanumeric Sequencing involves the alternating recitation of counting and the alphabet. We report data on the use of this measure with two clinical samples of persons with multiple sclerosis, having either the chronic progressive (n = 23) or relapsing-remitting form (n = 52) of the disease. Patients were administered Alphanumeric Sequencing and several other tests of information-processing speed/capacity and short-term memory. Chronic progressive MS patients performed worse than 23 healthy controls on both the speed and error components of the test, while relapsing-remitting patients were worse than 35 controls only on the total time to complete the task. The time score was correlated with several measures of information processing and short-term memory.