A few studies tried to evaluate the effects of lemon juice supplementation in patients with calcium oxalate nephrolithiasis, but the findings were flawed by the retrospective, observational design of the study or by the too small sample size that limited the power of statistical analyses and the reliability of the results. Thus, the protective effect of lemon juice supplementation against recurrence of stones in patients with calcium oxalate nephrolithiasis is worth investigating in adequately powered and designed trials.