Abstract: A wrist exerciser has a pair of coaxially mounted hand grip bodies. The hand grip bodies can be counter-rotated against a resistance to exercise the muscles in a user's forearms. A friction disk is sandwiched between the two hand grip bodies with a friction surface on one of the bodies bearing against the friction disk. The two hand grip bodies are biased toward each other to clamp the friction disk. The amount of bias force can be varied to set the amount of resistance to the rotation of the hand grip bodies relative to each other. The exerciser includes a spring connected to a member which is slidably mounted in a bore within one of the hand grip bodies. The member is prevented from rotating in the bore. The position of the member can be adjusted by turning an adjustment knob which is threadedly engaged with a threaded rod extending from the member. The bearing is located at one end of the spring. A thrust bearing between the adjustment knob and the hand grip body makes the adjustment knob easy to turn.