Recurrent laryngeal nerve (RLN) paralysis can occur following systematic upper mediastinal nodal dissection by radical surgery for primary lung cancer. However, there have been very few reports. We retrospectively reviewed the clinical data of 365 consecutive patients who underwent radical surgery for primary lung cancer with an over 6-month observation period in our institution from July 2010 to August 2015. There were 22 cases that experienced hoarseness after lung cancer surgery (6.0%). We could identify the movement of the vocal folds with a laryngoscope in 21 out of 22 cases (95.5%), because one patient refused to have the examination. Categorical variables were analyzed with Fisher’s exact test and continuous variables with the student’s-t test. P < 0.05 was considered statistically significant for all tests. Hoarseness subsequent to radical surgery for primary lung cancer arose in 16 out of 308 (5.2%) cases of video-assisted thoracic surgery (VATS) including robotic VATS, in contrast with six out of 88 cases (6.8%) of open thoracotomy. All patients who experienced hoarseness had received upper mediastinal nodal dissection. Patients who had received right upper nodal dissection experienced hoarseness in eight out of 150 cases (5.3%), in contrast to 14 out of 84 cases (16.3%, P = 0.020) for left upper lymph node dissection. Laryngoscopic examination revealed that five patients (23.8%) were diagnosed with right RLN paralysis and 15 (71.4%) as left. One patient who underwent VATS right upper lobectomy with upper mediastinal and subcarinal nodal dissection had left RLN paralysis. There was a patient (4.8%) who did not suffer from RLN paralysis, and one patient refused to undergo the examination. Eleven out of 18 patients (61.1%) were identified to improve the diagnosis of disorders of the vocal cords with the laryngoscope. It took one to 24 months (average 6.5 months) to improve the movement of the vocal cords observed with the laryngoscope. In addition, fourteen out of 19 cases (73.7%) were recognized for the improvement of their hoarseness. It took one to 28 months (average 10.4 months) to improve the voice disorder after surgery. In our cohort, 8.4% of patients who underwent systematic upper mediastinal lymph node dissection had hoarseness as a subjective symptom. However, 73.7% of patients who suffered from hoarseness and 62.5% of patients who were identified as having disorders of the vocal cords improved in more than two years.