Weakness after carpal tunnel release is common. Potential factors are transverse carpal ligament (TCL) division, incision or pillar pain, swelling, and flexor tenosynovitis. In the study reported here, we examined the effect of TCL division on reactive grip-strength changes. A minimally invasive technique was used with local anesthesia and sedation for TCL release in 41 hands. Total grip strength and individual-digit grip strength were measured using a computerized dynamometer. These measurements were taken preoperatively; immediately after TCL division; and 1, 3, and 5 weeks postoperatively. There was no significant difference between total grip strength measured preoperatively and strength measured immediately after TCL division, but the difference between these values and strength measured 1 week postoperatively was significant. Preoperatively, index fingers contributed 25.3% of total grip strength; long fingers, 31.3%; ring fingers, 27.0%; and small fingers, 16.4%. These contributions were approximately the same after TCL division.