Two bonded dissimilar anisotropic thin films of equal thickness h with an interfacial crack under an anti-plane singularity such as a screw dislocation or an anti-plane line force is analyzed by conformal mapping technique. The image forces on the screw dislocation, the energy release rate, and stress intensity factor are explicitly derived in terms of complex potentials. The interaction problems in two bonded orthotropic films are exemplified and the results for various particular cases of the present study are compared with the known solutions, demonstrating the versatility of this study. (C) 2001 Elsevier Science Ltd. All rights reserved.