Purpose: To evaluate the relationship between the presence of kidney stones and COVID-19.Materials and methods: Patients, who were treated for COVID-19 as outpatients as well as inpatients in the ward and/or ICU of two different secondary and tertiary care centers between July 15, 2020, and December 31, 2020, and aged ≥18 years were retrospectively evaluated. The patients were divided into two subgroups based on the presence of kidney stones, and then the patients with kidney stone were categorized into three groups: those who were treated in an outpatient setting (Group 1), those who were treated in the ward (Group 2), and those who were treated in the intensive care unit (Group 3).Results: The total of 1,335 COVID-19 patients included in the study. Kidney stone was present in 31 (6.9%) of 450 outpatients, 41 (8.9%) of 460 inpatients treated in the ward, and 60 (14.1%) of 425 inpatients treated in the intensive care unit. In Group 1, the duration of COVID-19 treatment was significantly longer in patients with kidney stone than patients without kidney stone (8.1±1.7 vs. 6.8±2.2 days, p=0.01). In Group 2 and in Group 3, the mean hospitalization duration was significantly longer in patients with kidney stone than in those without kidney stone (9.1±3.7 vs. 6.2±2.1 days, p=0.007; 19.1±8.1 vs. 11.3±6.2 days, p=0.001, respectively). Conclusion: The duration of COVID-19 treatment was longer and the COVID-19 infection was more severe in those with kidney stones.