The propagation of plane waves in a prestressed elastic solid with incremental elastic coefficients possessing orthotropic symmetry is discussed. Two types of plane waves, called quasi‐Pand quasi‐Swaves, are shown to exist. An expression for the group velocity of these waves is obtained. The velocities of quasi‐Pand quasi‐Swaves are found to depend on the angle of propagation. The reflection coefficients of these waves incident at the free surface of a prestressed elastic half‐space are derived. Critical reflection of quasi‐Pand quasi‐Swaves has been discussed. It is found that while quasi‐Swaves always have critical reflection, quasi‐Pwaves can have critical reflection only if incremental elastic coefficients satisfy a certain condition.