An operable anti-tip assembly adapted for a wheelchair, and characterized by: a control mechanism including a mounting unit that is adapted to be mounted to a rear end portion of the wheelchair in a removable manner, and that defines a mounting space extending in a first direction, and a positioning unit that is disposed in said mounting space in a resiliently restorable manner and that includes a first engaging portion; and an anti-tip mechanism including an anti-tip strut unit that is movably inserted through said mounting unit in a second direction inclined with respect to the first direction and that includes a second engaging portion, and a resilient member that is connected to said mounting unit and said anti-tip strut unit and that urges said anti-tip strut unit to move away from a ground surface; wherein said positioning unit is changeable within said mounting space between a locking state, where said first engaging portion engages said second engaging portion to prevent said anti-tip strut unit from moving relative to said mounting unit in the second direction, and an unlocking state, where said first engaging portion disengages from said second engaging portion to allow said anti-tip strut unit to be urged by said resilient member to move relative to said mounting unit in the second direction and away from the ground surface. a control mechanism including a mounting unit that is adapted to be mounted to a rear end portion of the wheelchair in a removable manner, and that defines a mounting space extending in a first direction, and a positioning unit that is disposed in said mounting space in a resiliently restorable manner and that includes a first engaging portion; and a mounting unit that is adapted to be mounted to a rear end portion of the wheelchair in a removable manner, and that defines a mounting space extending in a first direction, and a positioning unit that is disposed in said mounting space in a resiliently restorable manner and that includes a first engaging portion; and an anti-tip mechanism including an anti-tip strut unit that is movably inserted through said mounting unit in a second direction inclined with respect to the first direction and that includes a second engaging portion, and a resilient member that is connected to said mounting unit and said anti-tip strut unit and that urges said anti-tip strut unit to move away from a ground surface; an anti-tip strut unit that is movably inserted through said mounting unit in a second direction inclined with respect to the first direction and that includes a second engaging portion, and a resilient member that is connected to said mounting unit and said anti-tip strut unit and that urges said anti-tip strut unit to move away from a ground surface; wherein said positioning unit is changeable within said mounting space between a locking state, where said first engaging portion engages said second engaging portion to prevent said anti-tip strut unit from moving relative to said mounting unit in the second direction, and an unlocking state, where said first engaging portion disengages from said second engaging portion to allow said anti-tip strut unit to be urged by said resilient member to move relative to said mounting unit in the second direction and away from the ground surface.