Background: The factors related to fluid intake adherence among patients undergoing hemodialysis have been explored in many studies. However, most of these were conducted in Western countries and have produced inconsistent results. A study of this issue in Indonesia, a tropical country with strong herbal medicine traditions, may show different results. In addition to demographic characteristics, self-efficacy is a standard measurement used in chronic care management activities such as hemodialysis treatment. Understanding the reasons behind patient nonadherence in Indonesia may help nurses better manage the fluid intake of patients. Purpose: This study was designed to determine the factors that predict patient adherence to fluid intake restrictions. Methods: A cross-sectional study was conducted on 153 patients undergoing hemodialysis at two hospitals. Intradialytic weight gain over a 1-month period was recorded to assess the participants’ adherence to fluid intake restrictions. Intradialytic weight gains of more than 2 kg was considered to be nonadherent. A daily urine output and level of thirst were also recorded. The participants completed an adapted self-efficacy questionnaire, Swedish Fluid Intake Appraisal Inventory, and the data were analyzed together with demographic characteristic and clinical parameters using hierarchical multiple regression. Results: The results revealed that most of the respondents did not adequately adhere to fluid intake restrictions (59.5%). Intradialytic weight gain was shown to strongly correlate with self-efficacy (p < .05, β = −.201), gender (p < .05, β = −.179), educational background (p = .05, β = .159), and urine output (p < .05, β = −.168). Demographic characteristic explained 10.6% and self-efficacy explained 3.9% of the variance in fluid adherence. Conclusions/Implications for Practice: Female participants with higher self-efficacy scores reported the lowest average level of intradialytic weight gain, indicating better adherence to fluid intake restrictions. Several demographic factors as well as self-efficacy were identified as potential predictors of fluid intake restriction adherence. Therefore, measuring self-efficacy periodically is a good initial step toward detecting those patients who are at higher risk of noncompliance with fluid intake restrictions.