Objective Our objective was to investigate the correlations of interdialytic weight gain (IDWG) with the Malnutrition Inflammation Score (MIS) and other nutritional markers, especially when age difference is considered. Design This was a cross-sectional study. Setting The setting was an outpatient hemodialysis (HD) center in a community hospital. Patients Excluding those with obvious inflammatory diseases, hospitalizations, and major surgery within the preceding 3 months, we enrolled all anuric patients who had undergone maintenance hemodialysis three times a week for >1 year. In total, 84 women and 80 men were enrolled. Their age (mean ± SD) was 57.9 ± 13.0 years. Main Outcome Measures The conditions of food intake and nutritional status were evaluated with MIS items. Concerning IDWG, the average of 12 sessions within 4 weeks was used. The relative IDWG (RIDWG) was calculated as IDWG divided by the respective dry weight. Other laboratory data were obtained from routine monthly sampling. Results Whereas IDWG and RIDWG had no significant correlation with any of the MIS items in younger patients (<65 years old; n = 106), RIDWG had a positive correlation with the severity of insufficient food intake, gastrointestinal upset, functional incapacity, and wasting of muscle and subcutaneous fat in older patients (≥65 years old; n = 58). On the other hand, IDWG and RIDWG had no significant correlation with serum albumin level in younger and older HD patients, respectively. Conclusions Our findings suggest that in older HD patients, the greater that the RIDWG is, the poorer the nutritional status will be. However, there is still controversy regarding IDWG and RIDWG as nutritional markers in HD patients.