In a five-year case-control study (1988 to 1993) at Assir Central Hospital (ACH), Abha (8,000 feet above sea level), Saudi Arabia, 92 of 129 patients suspected of deep venous thrombosis (DVT) were studied with ascending contrast venography (CV) (74 patients, 80.4%) or Doppler ultrasonography (DUS) (18 patients, 19.6%). Female-to-male ratio was 2.3 to 1. Age range of patients was twelve to ninety years; mean age was 44.45 yrs +/- 17.38 years. DVT hospital incidence was 18 per 10,000 admissions. The most common associated factors included immobilization due to chronic diseases (21.7%), trauma and surgery (19.6%), and pregnancy and oral contraceptives usage (16.3%). The most common symptom and sign were limb pain and tenderness (95.6%). Limb swelling was noted in 93.5% of patients. The left lower limb was more commonly affected than the right. There was a definite increase of DVT during the winter months. Altitude was not a contributory factor. Pulmonary embolism was the greatest complication.