Effects of continuous isomolar infusions of acetic acid (AA) or sodium acetate (NA) infused into the rumen (RU) or into the abomasum (AB) were evaluated on feeding behavior, dry matter intake (DMI), and metabolic response of cows. Six rumen-cannulated multiparous Holstein cows (11.8 ± 4 d in milk) were utilized in a 6 × 6 Latin square design experiment balanced for carryover effects with a 2 × 3 factorial arrangement of treatments. Treatments were AA and NA, with sodium chloride (NC) as a control, infused at a rate of 0.75 mol/h (0.5 L/h) into the RU or AB for the first 8 h following feeding with a rest day between infusion days. Treatment sequences were assigned to cows randomly. Feeding behavior was recorded by a computerized data acquisition system and blood was sampled at 0, 4, and 8 h relative to the start of infusion. Data were analyzed by ANOVA; the model included the fixed effects of treatment and period and the random effect of cow; treatments were compared with preplanned contrasts. We hypothesized that AA was more hypophagic than NA, and that infusion into the AB was more hypophagic than into the RU. Treatments decreased DMI 30% (4.3 kg/8h vs. 6.1 kg/8h, P < 0.01) compared with NC by decreasing meal frequency (P < 0.05) but their effects on DMI differed (interaction P < 0.01); NA-RU did not reduce DMI (7.0 kg/8h), while AA-RU (2.6 kg/8h), AA-AB (3.7 kg/8h) and NA-AB (4.0 kg/8h) decreased DMI compared with NC. Treatments did not affect DMI during the rest day (P > 0.05). All treatments increased plasma acetate and β-hydroxybutyrate concentrations over time (interaction, P < 0.001) and decreased plasma insulin concentration (P = 0.01) compared with NC. AA-AB decreased plasma glucose concentration over time (interaction, P = 0.01) compared with other treatments and NC. Plasma NEFA concentration was increased over time with higher concentrations for AA-AB and AA-RU compared with other treatments and NC (interaction, P = 0.02). Sodium acetate did not decrease DMI compared with control or the other treatments but the reasons for the different effects are not known.