Essential oils (EO) are natural plant secondary compounds prevalent in various plants. They are characterized by an intense aroma and bioactive properties, which may influence intake, digestion, metabolism, performance and milk composition of livestock. In the present study, a commercial powdery product containing EO from eucalyptus, thyme and anise was fed at 25 g/day (= 5 g EO; following the producer’s recommendation) to 24 cows yielding 36 kg/day of energy-corrected milk (ECM). Feed intake and milk yield were recorded. The milk composition was analysed using an infrared spectrophotometer, and the coagulation properties were determined on a Lattodinamografo. Milk total phenol content and antioxidant capacity were photometrically analysed. The EO feeding resulted in a dry matter intake (DMI) which was higher by 4% compared to the control group, whereas ECM (32.8 vs 32.0 kg/day) was slightly but not significantly higher. Feed efficiency (1.67 vs 1.64 kg DMI/kg ECM) was not affected. The EO supplementation did not affect milk composition (fat, protein, lactose and urea) and coagulation properties. It significantly increased somatic cell count, but to an uncritical level. The EO did not enhance total phenol content and antioxidant capacity of milk. In conclusion, the investigated EO mix could be used for its main purpose according to the producer’s statements, namely to combat respiratory diseases, without impairing milk yield as well as milk compositional and technological properties. Higher supplementation levels than those recommended might have more pronounced effects on the variables investigated. Further studies are required to evaluate if the supplementation with higher doses would be favourable or unfavourable.