Studies have shown that the use of a conventional sling backrest in a wheelchair may have a negative impact on the posture and health of users. To avoid such problems, this backrest is often replaced by a back cushion on a rigid surface. However, the use of the latter deprives many wheelchair users of the advantages provided by the sling backrest (easy folding, lightweight, low cost, unobtrusive, simplicity of design). In an effort to maintain these features while providing adequate posture, a new backrest was designed according to specific criteria. The “flexible contour backrest” has been developed so that it can be adapted to a person's back contour with stays, adjustable straps, and curved back posts. Preliminary comparisons done by some experts with commercially available backrests showed that design criteria were reached at 62.9% by the back cushion on a rigid surface, at 64% by the sling backrest, and at 67.7% by the adjustable-tension backrest. On the other hand, design criteria were reached at 80% by the new flexible contour backrest because its design brings together most of the positive features provided by these other backrests (easy to fold, light weight, unobtrusive, airy) as well as providing adequate posture and better fit to the user's morphology.