Feed additives that claim to reduce enteric methane exist. However, these feed additives have not been evaluated on how they affect dairy cattle performance. Therefore, the objective of this study was to evaluate the effects of a garlic extract and citrus flavonoid feed additive on the performance of dairy cows. Multiparous crossbred dairy cattle (n = 48) were housed at the Southwest Regional Dairy Center in Stephenville, TX. All cows were housed in a sand-bedded freestall pen equipped with a Calan Broadbent feeding system (American Calan, Inc., Northwood, NH) to allow for individual feedings. The control diet (CON) was the basal total mixed ration. The treatment diet (TRT) had the feed additive top-dressed daily as 15 g of a pelleted supplement. Both diets were offered at 110% of the previous day’s consumption. Orts were collected before daily feeding and weighed for determination of ad libitum consumption. All cows were adapted to the diets and facilities for 14 d followed by a 77-d data collection period. Cows were milked 3 times daily and milk yield was averaged daily. Milk samples were collected at each milking one day each week and were averaged daily. Data were analyzed as a randomized complete block design, with pen serving as the random blocking factor. The MIXED procedure of SAS (SAS Institute Inc., Cary, NC,) was used to evaluate the fixed effects of treatment with day as a repeated measurement on the subject of cow. No statistical differences were observed in daily intake (P = 0.63) or milk yield (P = 0.33) at 58.70 and 58.00 and 46.10 and 44.00 kg/day between CON and TRT, respectively. No significant differences existed (P > 0.05) between fat percent at 4.10 and 4.20, protein percent at 3.30 and 3.30, urea percent at 11.20 and 11.40, acetone percent at 0.04 and 0.05, lactose percent at 4.80 and 4.80, and solids nonfat percent at 8.90 and 9.10 for CON and TRT, respectively. The data suggests that the addition of the garlic extract and citrus flavonoid feed additive does not affect dairy cow performance.