Background and purpose Specific respiratory tract infections, including COVID-19, may cause smell and/or taste disorders (STDs) with increased frequency. The aim was to determine whether new-onset STDs are more frequent amongst COVID-19 patients than influenza patients. Method This was a case-control study including hospitalized patients of two tertiary care centres. Consecutive patients positive for COVID-19 polymerase chain reaction (cases) and patients positive for influenza polymerase chain reaction (historical control sample) were assessed during specific periods, employing a self-reported STD questionnaire. Results Seventy-nine cases and 40 controls were included. No significant differences were found in basal features between the two groups. New-onset STDs were significantly more frequent amongst cases (31, 39.2%) than in the control group (5, 12.5 %) [adjusted odds ratio 21.4 (2.77-165.4, P = 0.003)]. COVID-19 patients with new-onset STDs were significantly younger than COVID-19 patients without STDs (52.6 +/- 17.2 vs. 67.4 +/- 15.1, P < 0.001). Amongst COVID-19 patients who presented STDs, 22 (70.9%) recalled an acute onset and it was an initial manifestation in 11 (35.5%). Twenty-five (80.6%) presented smell disorders (mostly anosmia, 14, 45.2%) and 28 (90.3%) taste disorders (mostly ageusia, 14, 45.2%). Only four (12.9 %) reported concomitant nasal obstruction. The mean duration of STD was 7.5 +/- 3.2 days and 12 patients (40%) manifested complete recovery after 7.4 +/- 2.3 days of onset. Conclusion New-onset STDs were significantly more frequent amongst COVID-19 patients than influenza patients; they usually had an acute onset and were commonly an initial manifestation. The use of STD assessment in anamnesis as a hint for COVID-19 and to support individuals' self-isolation in the current epidemic context is suggested.