Two cementless hip arthroplasty models with a modular neck made titanium alloy were submitted to cyclical loading in air, in physiological solution, and in a solution for accelerated corrosion tests in order to study the damage process of modular couplings. Thereafter, on one of the two models a series of tests were conducted in order to evaluate the quality of debris produced by the couplings. The parameters of testing adopted allow us to estimate the production of metallic debris observable in vivo with this type of prosthetic stem. The results show that the couplings of modular prostheses may be the source of metallic debris. The amount of debris produced depends on the geometry of the coupling and of the entire implant. Good planning and realization of the couplings, however, reduce the phenomenon that is negligible as compared to other potential sources of debris such as the surface of the stem or of the prosthetic head.