Abstract: A collapsible walker that includes a front frame, a pair of side frames, and a pair of levers. The front frame has a pair of skewed surfaces. The pair of side frames are hingedly attached to the front frame and are parallel thereto when the collapsible walker is in the closed position and are perpendicular thereto when the collapsible walker is in the open position. The pair of side frames have notches therein with skewed surfaces, with the pair of skewed surfaces of the front frame being vertically movable in the notches. The skewed surfaces of the pair of side frames move relative to the pair of skewed surfaces of the front frame as the collapsible walker is achieving the open position, until such time as it achieves the open position in which the pair of skewed surfaces of the front frame and drop down in the notches and mate with, and abut against, the skewed surfaces therein so as to prevent relative rotation therebetween and further rotation of the pair of side frames in both directions.