Achilles tendon pain or rupture after fluoroquionolone treatment has been described as an uncommon adverse effect. We report two patients with ciprofloxacin-associated Achilles tendon disease, one with histopathological examination. Microscopic evaluation showed irregular collagen fiber arrangement, hypercellularity, and increased interfibrillar glycosaminoglycans. These pathological features are also seen in tendon overuse injuries in athletes.