Background. Acquired flatfoot deformity goes ahead with a partial or complete rupture and thus insufficiency of the tibialis posterior tendon. We present the results of flexor digitorum longus transfer and medial displacement calcaneal osteotomy to reconstruct the acquired deformity. Material & Methods. Twenty two patients (24 feet) with an average age of 58 (36–75) years were operated on for acquired flexible flatfoot deformity. Two patients had a bilateral procedure. Patients were seen pre-and postoperatively in order to evaluate following parameters: AOFAS hindfoot score, visual analogue scale for pain (0–10), the tarsometatarsal angle on lateral and ap standing x-rays, the cuneiform heights and talocalcaneal angle on lateral standing x-rays and subjective postoperative satisfaction score (1-worst to 5-best). Average time of follow-up was 24.7 months (12–48). Results. The AOFAS hindfoot score could be increased from 46.4 to 89.5 points, the visual analogue scale for pain decreased from 6.6 to 1.1. The average satisfaction score was 4.5 points with one patient scoring 2 and another one scoring 3. All the other patients scored either 4 or 5. All radiological parameters could be improved. Following complications were seen: one recurrence, two patients with irritation of the sural nerve, one patient with hypesthesia of the big toe. The calcaneal screws had to be removed in 3 patients. Conclusion. Flexor digitorum longus transfer together with medial displacement calcaneal osteotomy gave satisfactory results for the treatment of acquired flatfoot deformity. All radiologic parameters were improved