Oscillating the dietary crude protein (CP) from adequate to deficient levels compared with continuously feeding adequate CP has increased N use efficiency in sheep and beef cattle. We hypothesized oscillating dietary CP to dairy cows could maintain milk protein production while feeding a lower average dietary CP content. Our objective was to determine whether oscillating CP content of a diet marginally deficient in metabolizable protein compared with feeding a constant CP concentration alters milk production and N utilization. Thirty Holstein cows (119 ± 21 DIM) were used in a randomized block experiment with a 10-d covariate period and a 50-d treatment period. Diets were adequate CP fed continuously (CP+; 16.2% CP of DM); marginally deficient CP fed continuously (CP−; 14.1% CP); or 24-h oscillations from adequate (16.2% CP) to deficient CP (11.9% CP) to be on average equal to CP− (OSC). Data were analyzed with a mixed model with fixed effects of diet, week, the interaction and random effects of block and block by diet. Compared with CP−, dry matter intake tended to be lower for OSC (23.2 vs. 22.2 kg/d; P < 0.11) but similar to CP+ (22.9 kg/d; P < 0.59). Milk yield was greater for CP+ compared with CP− (36.6 vs 35.1 kg/d; P < 0.02) and similar between CP− and OSC (35.3 kg/d; P < 0.78). Milk protein yield was similar among treatments (avg. 1.07 kg/d; P ≥ 0.14). Milk urea-N (MUN) was higher for CP+ (12.8 mg/dL; P < 0.01) and tended to be higher for OSC (10.9 mg/dL; P < 0.10) compared with CP− (10.2 mg/dL). Higher average MUN for OSC could be from enhanced urea recycling. Cyclical patterns in milk and protein yields and MUN occurred with OSC. On days cows received adequate CP, milk and milk protein yields and MUN were lower (P ≤ 0.04) compared with days cows received deficient CP (milk: 34.6 vs. 36.1 kg/d; protein: 1.00 vs. 1.05 kg/d; MUN: 9.3 vs 12.5 mg/dL), which indicates production lagged 1 d in response to changes in dietary CP. Overall, the results suggest oscillating CP may improve N utilization through enhanced urea recycling, but additional nutrients may be needed to compensate for reduced intake and to enhance production.