Liquid shims are often used to fill tolerance gaps between bolted joint plates in aircraft structures. This paper presents an experimental and numerical study of the effect of liquid shim and pretension on the quasi-static behavior of aluminum joints with titanium bolts. Single shear butt joint specimens with and without liquid shim, and with two levels of bolt pretension, were tested to failure. The experiments were simulated using FE-models which include elastic-plastic material behavior and a ductile damage model. Both the simulations and the experimental tests showed that the level of pretension had a small effect on the failure load. On the other hand, the specimens with liquid shims had a significantly lower strength and stiffness than the specimens without the shims.