Three groups of six porcine deep flexor tendons were repaired with a locking loop modified Kessler core suture using 4-0 braided polyester. Silfverskiöld repairs were performed using 6-0 monofilament nylon taking bites 2, 4 and 6 mm from the cut end of the tendon. The repairs were tested to failure and record made of bulking, mode of failure, force to produce a 3 mm gap and the ultimate strength. Data were analysed using one-way ANOVA, with analysis of mode of failure using the Chi-squared test. The 4 mm repairs were significantly stronger than the 2 mm for all parameters but there was no difference between the 4 mm and 6 mm repairs. We feel that optimal repair strength is provided using bites 4 mm from the cut tendon ends. Taking bites further from the cut end has no significant benefits and carries the theoretical risk of increasing the work of flexion.