Around 90% cancers form solid tumours. The major differences between tumour and normal tissue lie in the cancerous growth and angiogenic vasculature. Accurate real-time imaging of tumour size and changes in tumour vasculature is of great significance in the context of evaluating tumour growth and therapeutic effects during cancer therapy. While most real-time imaging systems can not fulfill both purposes simultaneously, high resolution imaging ultrasound seems quite promising. Our laboratory has established the VisualSonics, Vevo770 ultrasound system for monitoring tumour size and scrutinizing its vasculature with a powerful Doppler function allowing real-time studying of deep, small tumour vessels. We used the system to monitor tumour size and vasculature of subcutaneous xenograft and synergic mouse tumours derived from injection of 4 different cancer cell lines including A549, A431, SW620, and CT26. For each specific cancer cell line, three animals were used. After 3 weeks, when tumours are palpable, we found the ultrasound system was very accurate in measuring tumour size as compared to the direct manual measurement of removed tumours using a calliper. Meanwhile, the Doppler function of the system was able to clearly display tumour vasculature in fine details. Our results suggest that high resolution ultrasound system is capable of accurate measurement of tumour size in real time and more importantly, it's a powerful and economic modality for observing tumour vasculature and for cancer gene therapy studies using bacterial-mediated oncolytic gene therapy.