Objective Internal nasal valve collapse (IVC) is a common functional complication of rhinoplasty and injecting hyaluronic acid is one of the treatment options available, but its effectiveness has never been evaluated. The objective of this study was to assess the evolution of IVC after injection of hyaluronic acid using objective and subjective measures of nasal obstruction. Study Design A prospective interventional study was conducted. Methods Adult patients consulting for nasal obstruction after (septo)rhinoplasty and diagnosed with IVC were included. Patients underwent 4-phase rhinomanometry, completed nasal obstruction symptoms evaluation (NOSE) and visual analog scale (VAS) questionnaires and received hyaluronic acid injections. Measurements were repeated immediately, one month and one year later. The primary outcome measure was the proportion of patients below the rhinomanometric diagnostic threshold for IVC at one month. Results Among the 22 patients included, 20 (91%) had rhinomanometry measurements below the diagnostic threshold for IVC one month after injection. It decreased to 53% (8/15 patients) at one year post injection. The mean NOSE score decreased from 74.5 (± 18.0) before injection to 35.2 (± 23.3) after injection (p \ 0.0001). The mean VAS score decreased from 7.0 (± 1.4) before injection to 3.4 (± 1.9) after injection (p \ 0.0001). In these patients with post-(septo)rhinoplasty IVC, hyaluronic acid injection into the internal nasal valve substantially improved subjective and objective measures of nasal obstruction. Conclusion These results suggest hyaluronic acid injection (performed as described) is an effective treatment for IVC and is an excellent alternative to surgical treatment.