The tendo achilles is one of most important tendon in human body which often injured through direct trauma or indirect stress on a weakened tendon. Longer the duration after injury the injured parts likely to move apart, fibrosis and degeneration leading to difficulty in repair or reconstruction. Usually a phase of 4 weeks or more without specific treatment is regarded as chronic or neglected rupture. Different authors described many management protocols about the tendo achilles rupture but there is no procedure of choice for neglected rupture with long gap. Prospective case series of 21 patients of neglected tendo achilles rupture with long gap treated with flexor hallucis longus tendon (FHLT) transfer was taken for study from January 2019 to December 2020 in Mymensingh Medical College Hospital, Bangladesh. Average age of patients was 39.47 years with range 22-65 years. Fifteen (15) cases of traumatic rupture in this study with average age 32.66 years and pathologic 6 cases with average age 56.5 years were recorded. We grafted FHLT from channel by incising Henry's knot. Krackow et al.'s technique was followed for tendon mobilization and bone fixation. We made procedure simpler and cheaper; instead of using interference screw the sutured tendon pulled through the heel and anchored over rubber tube or button by Cole method. Post-operative complications were less with one patient with superficial infection which eventually recovered 3 cases of mild pain and 2 cases of numbness. Questionnaire for surgical outcome measure are satisfactory in 19 patients (90.47%). Final follow up AOFAS score at 6 month (91.61±5.41) was highly significant (p<0.001) in comparison to preoperative score (38.71±9.78). These are comparable to other study. Above mentioned scores indicate the reliability of the surgical system. But our study is a prospective case series with minimum cases. To establish the best procedure for neglected tendo achilles rupture with long gap we recommend further study with larger group and Randomized Controlled Trial (RCT) study among different procedure.