Background: Long thoracic nerve (LTN) neuropathy occasionally occurs in young people who engage in various sports. It may have a traumatic or non-traumatic etiology. The landmark manifestation of LTN neuropathy is scapular winging; however, it can also occur without scapular winging and specific magnetic resonance imaging findings.Case: An 18-year-old male complained of right-sided lateral chest pain for 7 months. He was treated with medication, trigger point injection, and physical therapy but showed no improvement. Electromyelogram findings suggested LTN neuropathy in the right lateral chest. We performed a serratus anterior (SA) plane block with ultrasound (US)-guided hydrodissection and achieved pain relief. Conclusions We report the successful treatment of LTN neuropathy with an SA plane block and US-guided hydrodissection.