Indocyanine green (ICG) angiography is a useful technology for assessing flap perfusion in reconstructive procedures. Flap clearance of ICG can help in assessing venous congestion. To the best of our knowledge, although a few reports have evaluated its use for venous congestion, no reports have assessed the viability and applicability of this technology for this purpose in muscle flaps. A 63-year-old female patient with right leg leiomyosarcoma post-tumor resection underwent reconstructive surgery with a hemi-gastrocnemius flap. A scan of the flap using ICG angiography showed slow clearance of dye in the flap compared to the rest of the body. On postoperative day (POD) 1, the flap was re-examined using an infrared camera and it showed evidence of retained dye. On the contrary, there were no clinical signs of flap congestion. Ultimately, the patient had a successful reconstruction and an uncomplicated postoperative course despite the inconsistent findings in ICG angiography. ICG angiography is a useful tool in assessing arterial perfusion of flaps. However, further evaluation is needed to gain clinical reliability and validity in the evaluation of venous congestion in muscle flaps. Its overall utility with respect to pedicled muscle flaps has yet to be established.