The purpose was to measure the outcome effects of a hydrotherapy program lasting 12 sessions on the rehabilitation of participants following joint replacement because of arthritis-related conditions. Sixteen volunteers at a postrehabilitation stage (15 women and 1 man, mean age 56.7 + 6.5 y) participated in a quasi-experimental design with simple interrupted time series aimed at improving range of motion around the hip joints, mobility (Berg Balance Scale, BBS), walking velocity in the timed up-and-go test (TUG) and scores on a quality-of-life scale (SF-36). One-way ANOVA statistics showed a significant effect between the pre- and posttest outcomes without differences between baseline and pretest for the extension and abduction of the operated hip, the BBS, the TUG, and the summary measures of the SF-36 (general, physical, and mental health). Findings suggest significant effects of the proposed treatment across the variables measured in participants with joint transplantations.