Chronic disorders of the Achilles tendon are commonly seen by the orthopaedic surgeon. In cases that are resistant to conservative treatment, a variety of surgical procedures have been utilized in the past. The indications for a previously described technique of flexor hallucis longus tendon transfer for reconstruction of chronic Achilles tendon rupture have been expanded to include further subsets of chronic Achilles tendinopathy, including rupture and tendinosis. We evaluated 20 patients (mean age 61) who underwent flexor hallucis longus transfer for treatment of chronic Achilles tendinopathy at a mean of 14 months following surgery. Our results were measured with the SF-36 survey, AOFAS Ankle-Hindfoot Scale, and Cybex strength and range of motion testing. Wound complications, tip-toe stance, and calf circumference were also assessed. There were no postoperative reruptures, tendinopathy recurrences, or wound complications. Despite a small loss of calf circumference, range of motion, and plantarflexion strength, 90% of patients scored 70 or higher on the AOFAS scale. SF-36 testing revealed significantly lower scores in the physical function category when compared with United States norms. Flexor hallucis longus tendon transfer/augmentation is a reasonable option for treatment of chronic Achilles tendinosis and rupture.