A weighted walker attachment system generally comprises a kit of weighted walker attachments that can be mounted to standard walker or other assistive perambulatory device for use in physical therapy and rehabilitation. A plurality of weighted attachments are provided and adapted to be mounted at a variety of locations on an assistive device. The weight of each attachment can be adjusted, as needed, for example, by adding or removing individual weighted plates mounted on a base plate that itself is removably mounted to the assistive device. In alternate kits, interchangeable weighted attachments can be provided in varying weights, distinguished by optical and/or tactile indicators, and selectively mounted on the assistive device, either as an accessory or in replacing a portion of the device, such as extensions provided on a walker's legs, in accordance with a therapeutic rehabilitation plan for an individual patient.