BACKGROUND Occasionally, tightening continuous suture loops in microvascular anastomosis may be difficult and troublesome when the loops are incorrectly tightened or entangled with each other, and the vascular endothelium may be injured by inadvertently grasping the lumen of the vessel with microforceps when tightening the intraluminal continuous suture loops. OBJECTIVE: To present a technique for tightening continuous suture loops in microvascular side-to-side anastomosis with a microneedle. METHODS: The technique for tightening continuous suture loops with a microneedle was presented in side-to-side microvascular anastomosis in chicken thighs arteries and rat common carotid arteries. After all the spiral continuous suture loops were loosely placed, the tip of the microneedle was used to precisely and gently tighten the second suture loop, then microforceps was used to pick this loop up and gently tighten it, while the body of the microneedle was gently applied to create a counterforce on the inner or outer surface of the vessel to help tighten the first loop under appropriate tension and place it in an appropriate position. RESULTS: With this technique we described, there is no need to change to any other surgical instruments during anastomosis, and these continuous suture loops in continuous microvascular anastomosis could be effectively tightened with a microneedle. And the technique was successfully applied in side-to-side microvascular anastomosis in chicken thighs arteries and rat common carotid arteries. CONCLUSION: Microneedle could be safely and effectively used as a microretractor to tighten the continuous suture loops in continuous microvascular anastomosis. The judicious and discreet use of a microneedle as a multifunctional instrument for functions other than suturing could minimize the exchange of instruments and improve operative efficiency.