Summary - The objective of the study was to compare, by gait analysis, the performance of an energy-storing prosthetic foot fabricated from composite materials, known as the 'Lambda Foot', and the conventional SACH foot. An attempt was made to show quantitatively that the Lambda Foot has better energy characteristics during gait. Three active unilateral below-knee amputees (2 females and 1 male) participated in the gait analysis. The Vicon motion analysis system and Kistler force plates were used in the study. Since the sample size was small, intr-comparison was made to give an indication of the overall trend. Stride characteristics (walking speed, cadence, single stance, and double stance) did not differ significantly between the two prosthetic feet. The Lambda Foot produced significantly larger ankle rotations at early and late stance, which more closely approximate to the natural ankle. The better energy characteristics of the Lambda Foot was shown in the large plantarflexion moment at the ankle of the Lambda Foot, when compared to the SACH foot. This was verified by the significantly higher energy values obtained at the ankle of the Lambda Foot. However, it is still approximately 60% less efficient than the normal, sound foot. The subjects expressed a liking for the Lambda Foot for being much lighter and offering a spring-like effect not experience with the SACH foot.