Eighteen multiparous and 15 primiparous lactating cows with a wide range of milk production (24 to 58 kg/d) were used in a crossover design experiment with a covariate period to evaluate the effect of isoenergetic diets with different levels of starch. Cows were randomly assigned to treatment sequence within parity and level of milk production. Dietary treatments were: high starch (HS) and low starch (LS; 31.8% and 23.9% starch of diet DM, respectively). Diets were formulated with similar levels of forages and energy by replacing dry ground corn by non-forage fiber sources and fat. During the 14-d covariate period, all cows received a common diet, which was a mixture of both treatment diets; milk yield data collected during the last 4 d of this period were used as covariate (cMY). Data were analyzed using the GLIMMIX procedure of SAS with fixed effects of treatment, period, parity, and cMY, and random effect of cow. Interactions evaluated were treatment by period, parity, and cMY and treatment by cMY by parity. In general, parity did not interact with treatments except for milk protein yield. Compared with LS, HS increased milk protein yield in multiparous cows of all production levels and in high producing primiparous cows, but not in low producing primiparous cows (interaction, P = 0.07). HS decreased MUN (13.5 vs. 15.5 mg/dL; SEM = 0.26) and increased nitrogen efficiency (26.9 vs. 23.5%; SEM = 0.59, both P < 0.01), but did not affect milk protein or fat contents. Overall, treatment diets did not affect yields of milk, energy-corrected milk, or milk fat yield. HS increased DMI and decreased feed efficiency in high producing cows, but not in low producing cows (interactions, both P < 0.05). Regardless of level of milk production and parity, HS increased DMI (25.9 vs. 25.4 kg/d; SEM = 0.50) and decreased total-tract NDF digestibility (31.7 vs. 39.0%; SEM = 0.73, both P < 0.05). Treatments did not affect body weight change over the 28-d periods. High starch isoenergetic diets increased intake and decreased NDF digestibility, but did not affect body weight change or yields of milk and energy-corrected milk in mid-lactation cows of different production levels and parities.