We present an operative technique and the results of intramedullary fixation of proximal phalangeal shaft fractures through a volar extra-tendon sheath approach. A J-shaped nail, which is a curved Kirschner wire sharply bent at the proximal end, was inserted from the palmar aspect of the proximal phalangeal base. Six fingers of the six patients (all male) were treated with this method. The mean age of the patients was 51 years (range, 20-69 years). There were four open and two closed fractures. All fingers attained successful fracture union and one of them had correction loss. No patient complained of pain at the final follow-up, and the average of total active motion was 223° (190° - 255°). This method may be an alternative for treatments of the proximal phalangeal shaft fractures because of its less invasive nature, although it does not offer anatomical reduction.