The purpose of this study was to investigate effects of fingernail length on active range of motion (AROM) of the fingers, speed of finger manipulation, number of words typed, and grip strength. Fifteen normal women (mean age, 30 years) performed measurements under four conditions with no attached fingernails and with fingernails extending 2, 1, and 0.5 cm beyond the tip of the finger. Analyses of variance showed that: 1) with fingernails of all extended lengths, grip strength measured on the first setting of the Jamar hand dynamometer decreased; 2) with fingernails 1 and 2 cm in length, AROM, grip strength on the second dynamometer setting, and finger manipulation decreased; and 3) with fingernails 2 cm in length, typing speed decreased (p < 0.05). Long fingernails limit flexion of the finger joints, particularly the metacarpophalangeal joints. Lack of finger flexion will limit excursion of long flexors and extensors in patients. It is recommended that patients cut their fingernails to a length of 0.5 cm to achieve optimal functional outcomes.