Water soluble InAs(ZnCdS) semiconductor nanocrystals with bright and stable emission in the near infrared (NIR) wavelength range have been prepared. The NIR semiconductor nanocrystals can be functionalized to enable imaging of specific cellular proteins. In addition, the utility of the NIR region for in vivo biological imaging is clearly demonstrated by the superior ability of InAs(ZnCdS) semiconductor nanocrystals to image tumor vasculature.