This paper presents theoretical and experimental evidence that boron dopants can be detected on in situ prepared Si(lll) (7 x 7) surfaces by scanning tunneling microscopy (STM). Using scanning tunneling spectroscopy (STS), imaged layers of different dopant concentration were produced by molecular beam epitaxy (MBE). The samples were ex situ cleaved and hydrogen passivated Si(110). The results indicate that STM/STS is suitable for two-dimensional dopant profiling in Si with extremely high lateral resolution.