We report a 16-month-old girl with varicella complicated by cellulitis, invasive Group A Streptococcus (GAS) infection and deep vein thrombosis. She presented with varicella lesions, fever and a painful firm tumefaction on the right lower leg (RLL). Ultrasound showed a local subcutaneous tissue thickening suggestive of cellulitis and antibiotics were initiated. Further swelling of the RLL motivated a second ultrasound that showed an obstructive thrombus for which she was started on enoxaparin. The blood culture confirmed GAS infection leading to directed antibiotherapy. Additional studies showed positive lupus anticoagulant, decreased protein S and antithrombin. She completed a 2-week course of intravenous antibiotics and anticoagulation therapy with clinical and laboratory markers improvement. However, 3 days later, a recrudescence of symptoms occurred and the ultrasound revealed a local abscess. Further amoxicillin treatment resulted on a complete resolution of symptoms. Doppler ultrasound after 1 month showed markedly increased vein patency.