As part of a study of landslides, geophysical methods of site investigation have been used in Columbia to determine their effectiveness in obtaining sub-surface information. The techniques used in this study included seismic refraction and electrical resistivity, and the sites selected were examples of different classes of landslide. The geophysical field data obtained were generally satisfactory and confident interpretation were possible. The results of seismic refraction surveys showed good correlation with borehole information and the rock, boulder and clay layers reported in the borehole logs corresponded to the different velocity layers indicated. The results of electrical resistivity soundings were affected by the moisture conditions, and where weathered layers exist within bands of rock they adversely affect the results obtained. However, electrical resistivity is useful in conjunction with seismic refraction for giving additional information on moisture conditions present.On sites where little borehole information was available, the geophysiscal methods gave good indications of likely soil and rock layers present along the transverse lines investigated. Broad indications of the relationships found between geophysiscal values and potential instability are given. The work of other investigators using geophysics on landslide problems is briefly reviewed.