OBJECTIVE: To report the case of a patient with paradoxical vocal cord motion (PVCM) disorder and its treatment with botulinum toxin. CASE REPORT: A 16-year-old, brown, female student born in São Paulo presented with a history of recurrent attacks of shortness of breath and stridor that had started suddenly 10 months ago. She was being treated for asthma during hospitalization for acute attacks that continued to recur despite the use of prophylactic medication. Spirometric test results were normal, so the patient underwent transnasal flexible laryngoscopy that showed laryngeal dyskinesia with PVCM. The patient was treated with 8 U of botulinum toxin injected into the lateral cricoarytenoid muscle. Endoscopy done after the procedure revealed significant reduction in the amplitude of abnormal adduction during inspiration, and the patient remained asymptomatic for the next 4 months. Afterwards she suffered another attack that was controlled again with fresh injections of botulinum toxin into the vocal cord. CONCLUSION: PVCM is characterized by dysfunctional coaptation of the vocal cords that adduct instead of abduct during inspiration1. It occurs episodically, causing airflow obstruction, dyspnea and stridor2,3. These symptoms are often attributed to asthma and treated accordingly without success; this results in the patients getting a diagnosis of treatment-refractory asthma4. The diagnosis of PVCM4 is made by demonstrating abnormal vocal cord motion on laryngoscopy, in a patient who has no evidence of altered lung function on spirometry5. Our patient was initially considered to be a case of asthma, but the lack of response to treatment suggested the alternative diagnosis of vocal cord dyskinesia. The detection of paradoxical movement of the vocal cords confirmed the diagnosis, and the patient responded well to treatment with botulinum toxin into the vocal cords. Therefore, the injection of botulinum toxin into the vocal cords can be considered as an alternative treatment for PVCM.