This study investigated effects of high inclusion of reduced-fat corn distillers grains with solubles (RFDG) with and without monensin on utilization and excretion of N, P, and S. The experiment was conducted with 36 Holstein cows in a randomized block design for 11 wk. Cows were blocked by parity, and days in milk and assigned to the following diets: (1) CON, a control diet; (2) DG, CON with RFDG included at 28.8% (% of DM) replacing soybean meal, soyhulls, and supplemental fat and P; (3) DGMon, DG with monensin at 20 mg/kg of DM. Milk and spot urine and fecal samples were collected in wk 3, 7, and 11 to determine dietary N, P, and S utilization and excretion. Data were analyzed with a model that included the fixed effect of diet, week, and 2-way interaction, and random effect of block and cow within block. Repeated measures were modeled. Compared with CON, DG and DGMon did not change crude protein content (17.6%) but increased rumen undegradable protein, P (0.48 vs. 0.36%) and S content (0.41 vs. 0.21%; DM basis). As a result, DG vs. CON decreased (P < 0.01) plasma and milk urea-N concentration, and urinary N excretion. Although P intake, plasma P concentration, and urinary and fecal P excretion increased (P < 0.05) for DG vs. CON, milk P secretion was not affected. Intake of S was greater (P < 0.01) for cows fed the DG vs. CON, resulting in greater (P < 0.03) plasma total S and sulfate concentration and urinary and fecal S excretion. However, milk S secretion was not affected by DG compared with CON. Monensin supplementation to the DG diet did not affect N intake, utilization, and excretion except that apparent N digestibility was lower (P < 0.04) compared with DG. In addition, DGMon did not affect P and S utilization and excretion compared with DG. This study suggests that a high inclusion of RFDG can decrease urinary N excretion but increase manure P and S excretion. However, monensin supplementation to a high-RFDG diet, overall, had minimal effects on N, P, and S utilization and excretion in lactating dairy cows.