Three hundred and twenty-two consecutive women aged 16-70 years who presented with objectively confirmed symptomatic venous thromboembolism (VTE) were studied to determine precipitating factors for thrombosis. One hundred and eighty-seven presented with deep vein thrombosis (DVT), 116 with either definite or possible pulmonary embolism (PE) and 19 with both DVT and PE. Injecting drug use (IDU) via femoral vein puncture was a common risk factor for DVT, associated with 21.4% of all cases of DVT and 52.4% of cases of DVT in women under 40 years. All women with drug-related thrombosis presented with DVT. None presented with symptomatic PE. A number of clinically diagnosed DVT associated with IDU were also documented, suggesting that IDU may be the most common risk factor for DVT in our region. DVT associated with IDU presents significant management challenges.