Single-walled carbon nanotubes(SWNT) in a polyethyl-eneghycol solution are a biocompatible transporters with strong op-tical absorption in the near-infrared region, in which the biological tissue is almost transparent with very low absorbance. Here, antibody-functionalized SWNTs for tumor early detection with photoacoustic molecular imaging in vivo are reported. To lay the groundwork for this goal and insure system stability, images were collected in tissue simu-lating phantoms to determine appropriate detectable concentrations of SWNTs. Preliminary in vitro and in vivo results showed that a high contrast and a high efficient targeting of integrin αvβ3 positive U87 human glioblastoma tumours in mice could be achieved. The nontox- icity of functionalized SWNTs has also been demonstrated in our ex-periment; this feature ensures that SWNTs can be used for clinical applications. This study suggests that photoacoustic molecular imag-ing with antibody-functionalized SWNTs has the potential to be an effective early tumor diagnosis method.