Objective To explore the efficacy of the auxiliary value of ultrasound-guided intercostobrachial nerve block for acute herpetic neuralgia at thoracic spinal nerve root 2. Methods We performed a retrospective review of patients with acute herpetic neuralgia at thoracic spinal nerve root 2 treated by CT-guided pulsed radiofrequency on dorsal root ganglia from June 2019 to September 2022. Patients were divided into control group (n=26) and block group (n=19) according to whether they received ultrasound-guided ICBN block.The curative effect was evaluated by Numerical Rating Scale (NRS) and pittsburgh sleep quality index (PSQI) at the time of pre⁃treatment (T0), and 1 mo (T1), 2 mo (T2) and 3 months(T3) after the treatment. Meanwhile, the proportion of patients consuming analgesics after treatment, withdrawal time of analgesics, and the incidence of postherpetic neuralgia (PHN) were also recorded. Results NRS and PSQI in both groups decreased significantly at different time points after treatments compared with T0 (P0.05). Compared with control group, block group showed lower NRS at T1 and T2 (P0.05); The proportion of patients consuming analgesics after treatment was lower in block group compared with control group at T1 (P0.05); Block group also showed shorter withdrawal time of analgesics than control group (P0.05). No significant difference was observed in PSQI at different time points after treatments and the incidence of postherpetic neuralgia between the groups (P0.05). Conclusions Ultrasound-guided intercostobrachial nerve block is an effective adjunct in alleviating pain and decreasing analgesics consumption for herpetic neuralgia at thoracic spinal nerve root 2.