The feet of Marfan patients are typically described as pes planovalgus. We evaluated the single-leg-stance footprint of 124 feet in 63 patients with the Marfan syndrome by using pressure-sensitive film and a Harris mat. Forty feet in 21 people with no history of foot problems were evaluated as normal controls. The medial and lateral aspects of the fore-, mid-, and hindfoot were assessed. The midfoot was further analyzed by dividing the medial midfoot force by the total midfoot force. The mean medial midfoot force/total midfoot force (MM/TM) in the control population was 11.1% (SD, 6.5%). Pes planus was defined as the MM/TM force >24.0% (mean + 2 SD). The mean MM/TM force in the Marfan group was not statistically different (16.0%) from controls. The distribution, however, revealed two distinct types of weight-bearing patterns. Of the Marfan group, 74.8% had medial forces within the standard distribution of the normal control population. Only 25.2% of the Marfan patients had forces that were outside the range of normal midfoot forces and were defined as pes planus. Analysis of the patient's ligamentous laxity and the foot function in the Marfan population revealed no statistically significant correlation to the type of weight-bearing pattern of the foot.