Obtaining a confirmed diagnosis of deep venous thrombosis (DVT) can sometimes be difficult with the conventional methods of venography and Doppler ultrasound. Since treatment of DVT should not be undertaken without a confirmed diagnosis because treatment is expensive, time consuming, and sometimes risky, it is very important to have a reliable investigation method. Thermal imaging provides this reliability. It has a high sensitivity for detecting DVT and it is noninvasive, risk-free, and cost effective. This article discusses the role of thermal imaging as the first step in confirming or excluding DVT to then determine whether it is necessary to use the conventional Doppler and venography methods.