The ideal zone II flexor tendon repair would be easy to perform, cause minimal scarring, and be strong enough to allow early active motion. A 6-strand loop suture technique devised by the senior author (T.M.T.) was studied in vitro. Forty flexor tendons were harvested from fresh-frozen human hands and divided into 4 groups of 10 tendons each. Each group of tendons was repaired with a specific technique: group 1, the modified Kirchmayr (modified Kessler) technique; group 2, the single-loop 2-strand technique described by Tsuge; group 3, Tsai's double-loop 4-strand modification of Tsuge's technique; and group 4, Tsai's double-loop 6-strand modification of Tsuge's technique. Gap resistance of each repair technique was recorded on a computer using a Differential Variable Reluctance Transducer (MicroStrain, Burlington, VT) and on videotape to record first gap formation, 1-mm and 2-mm gap formation, and maximum load. Statistically significant differences between groups were as follows: at first gap formation between the 2-strand and 6-strand loop suture techniques, and at maximum load between the modified Kessler and 4-strand, modified Kessler and 6-strand, 2-strand and 4-strand, and 2-strand and 6-strand loop suture techniques. The 6-strand double-loop suture technique had a higher tensile strength than the other techniques, as measured in this model at each stage in our experiment. The 6-strand double-loop suture technique simplifies flexor tendon repair. It improves the repair's strength and its resistance to gapping without increasing tendon handling or bulk. This increased repair strength allows us to pursue a more aggressive rehabilitation program.