Background Deep vein thrombosis (DVT) is a common health problem. Accurate diagnosis of DVT is essential to avoid potentially fatal acute consequences of pulmonary embolism. Aim The study aims to assess deep venous thrombosis (DVT) of the lower limbs and to analyze the related risk factors. Methods This is a retrospective study including 60 patients who were examined using Triplex Doppler imaging. The patients were referred to the imaging departments with symptoms of lower limb DVT. The risk of DVT was expressed as an odds ratio (OR) with 95% confidence interval. Multiple logistic regression analysis was used to detect the independent risk factors. P value <0.05 was considered a significant statistic. Results Among the Saudi patients in Najran, acute DVT was more prevalent than chronic one (56.7% vs 38.3%), while subacute is less frequent (5%). DVTs are more prevalent in females than males (60% vs 40%) and most commonly affect patients older than 40. DVTs affect the left lower limb veins more than the right limb (75% vs 15%) and are less frequent on both sides (10%). The left popliteal vein (PV) and left common femoral vein (CFV) were the most common sites for acute DVTs. Binary logistic analysis revealed the independent risk factors for developing lower extremity DVT; malignancy (OR = 2.84, 95% CI = 0.518–15.513), surgery (OR = 2.66, 95% CI = 0.411–17.281), trauma (OR = 2.30, 95% CI = 0.452–11.658), and diabetes and hypertension (OR = 1.53, 95% CI = 0.335–6.969). Conclusion Acute lower limb DVT was more prevalent than chronic one. Malignancy, surgery, trauma, diabetes mellitus, and hypertension were the most common risk factors for lower limb DVTs. Left popliteal and left common femoral veins were the most common sites of acute DVTs.