Objective: Surgeon-performed head and neck ultrasound (US) is increasingly used among otolaryngologists in office-based and surgical settings. However, it is unknown how formal US training affects otolaryngology residents' diagnostic workup of patients with cervical pathology. This study examined how a formal US course for residents affected their outpatient clinic US performance and diagnostic accuracy. Methods: We conducted a randomized cross-over trial, where 13 otolaryngology residents participated in a 6-h formal US course. Participants were randomized to perform head and neck US on four patient cases before and after completing the course. Eight patients with and without neck pathology were invited to participate as test cases. The ultrasound examinations were video recorded and anonymized before two consultants rated the US performance using the Objective Structured Assessment of Ultrasound Skills (OSAUS) scale. Otolaryngology residents wrote an ultrasound report with a diagnosis based on their US examination, which was used to calculate the specificity and sensitivity. Results: We found a statistically significant difference in the OSAUS score before compared to after the hands-on training (p =.035). The diagnostic accuracy also increased from 62% before the course to 75% after the course (p =.02). Specificity increased from 54% prior to the course to 62% following the course, and sensitivity increased from 64% prior to the course to 79% following the course. The intraclass correlation coefficient with “absolute agreement” was 0.63. Conclusion: This study demonstrates that short, formal ultrasound training can improve otolaryngology residents' ultrasound skills and diagnostic accuracy in an outpatient clinic setting. Lay summary: This study looks at the change of otolaryngology residents' diagnostic workup of patients after they take a formal ultrasound course and shows that they get better at using ultrasound and make more accurate diagnoses if they take a formal course. Level of Evidence: Level 2.