Coronavirus disease is a highly contagious disease caused by systemic acute respiratory syndrome coronavirus 2 with high mortality rates. We aimed to evaluate the relationship between serum d-dimer levels and tomography findings at the time of admission in patients diagnosed with coronavirus disease 2019 (COVID-19). This study included 94 patients, 48 women (51%) and 46 men (49%), diagnosed by PCR method. Patients without any suspicious findings on thorax tomography and having oxygen saturation above 90% at the time of presentation were included as the first group. Patients with suspicious tomography findings but having oxygen saturation above 90% were designed as the second group, and patients with both suspicious tomography findings for COVID-19 and low oxygen saturation levels (<90%) at the time of admission were taken as the third group. Patients with oxygen desaturation were significantly older than the patients with normal oxygen saturations (P = 0.001). Patients with thorax tomography findings were having significantly higher d-dimer levels (P = 0.001). Patients with oxygen desaturation were having significantly higher d-dimer levels than the patients with normal oxygen saturations (P = 0.001). There was a significant negative correlation between oxygen saturation and d-dimer levels in all patients with and without tomography findings (r = -0.301, P = 0.016). Similarly, there was a significant positive correlation between the oxygen saturation and the lymphocyte count (r = 0.300, P < 0.017). Thorax tomography and d-dimer levels significantly correlate in patients with suspected COVID-19 admission. It should be kept in mind that patients with low oxygen saturation and high d-dimer levels may have serious lung involvement.