Objectives: To describe the incidence of venous thromboembolism (VTE) in mechanically ventilated COVID-19 patients in an HIV endemic, resourced constrained setting. To describe the incidence of VTE in relation to HIV status and anticoagulant therapy, and to evaluate VTE-associated cardio-respiratory changes. To establish the contribution of HIV, anticoagulation therapy and other risk factors to mortality. Design: Prospective descriptive study. Setting: Single-center tertiary teaching hospital. Participants: One hundred and one consecutively admitted critically ill adult patients with COVID-19 acute respiratory distress syndrome. Interventions: Point of care ultrasound (POCUS) assessment of the lower limbs and the cardio-respiratory system was performed on intensive care unit (ICU) admission and repeated if clinically indicated. Measurements and main results: DVT was diagnosed by POCUS, whilst pulmonary embolism was diagnosed using a combination of clinical criteria and POCUS (echocardiography and chest wall ultrasound). VTE was diagnosed in 16/101 (16%) patients, despite 14/16 (88%) receiving prior therapeutic dosage of low molecular weight heparin. Clinically significant PE was diagnosed in 5/16 (31%) with 11/16 (69%) having DVT only. The majority of VTE patients, 12/16 (75%), demised 16/101 (16%) patients had HIV co-infection, and 4/16 (25%) with HIV had VTE. Valvular abnormalities were the most common cardiac abnormality with marked tricuspid regurgitation detected in 51/101 (51%). The absence of right atrial enlargement had a 93% negative predictive value for the absence of VTE. Univariate analysis did not demonstrate statistically significant individual risk factors for mortality. Conclusions: Mechanically ventilated COVID- 19 patients at ICU admission had a low incidence of VTE (16%). Therapeutic dose anticoagulation did not reduce mortality compared to prophylactic dosage. In contrast to findings from other studies, no individual risk factor contributed significantly to mortality, likely due to small sample size. POCUS is an ideal screening tool to aid in the assessment of critically ill patients.