BACKGROUND: The coronavirus disease (COVID-19) is characterized by a high prevalence of deep vein thrombosis (DVT), particularly in its severe form, but the incidence of DVT and risk factors for DVT in non-severe patients are still unknown. METHODS: The study enrolled 118 patients with non-severe COVID-19 infection which did not required hospital admittance. A duplex ultrasound and laboratory test were performed in all the patients after the first negative polymerase chain reaction SARS-CoV-2 test. RESULTS: DVT was identified in 50 (42.4%) patients with a median age of 48 years (interquartile range 30–85 years). Symptomatic DVT was present in 40 (80%) patients and was commonly seen in the Class I calf vein thrombosis (38 patients, 76%) (χ2 = 51.71, p < 0.001). The most significant risk factors for DVT were as follows: Increased C-reactive protein (p = 0.000), fibrinogen (p = 0.000), low lymphocyte count (p = 0.002), obesity (p = 0.017), and neutrophil count (p = 0.042). The multivariable logistic regression analysis revealed that a D-dimer cutoff point of 1253.5 μg/L showed a sensitivity of 92% and a specificity of 71%. CONCLUSION: Patients with increased inflammatory markers and obese patients after a non-severe COVID-19 infection should have an ultrasound examination to ensure early diagnosis of DVT and to prevent the occurrence of any complications.