This study examined the potential use of oregano essentail oil as a milk additive for purposes of reducing weaning age; increasing economic efficiency; promoting calf growth as well as for improving blood parameters and general health status of Holstein Friesian calves. Twenty-eight Holstein Friesian calves were allocated into three groups: (a) Control calves were fed with whole milk (n=10), (b) OreganoLow (n=9), and (c) OreganoHigh (n=9) calves were fed with whole milk, plus 100 and 150 mg/l oregano essential oil per kg milk respectively. The amount of the milk offered on daily basis was calculated as 10% of each calf live weight and was given in two meal times. All calves were kept in individual pens during experimental period. Calves got weaned following the consumption of daily 900 g of concentrate feed over three consecutive days. Results demonstrated that OreganoLow calves marked improved growth performance, earlier weaning age and lower farm costs (P < 0.05) compared to Control and OreganoHigh calves. To conclude, dietary oregano essential oil seems to be a potential liquid feed additive that improves feed efficiency, health status, growth performance, and that reduces diarrhea incidents, hastens weaning age and minimizes dairy farm costs when used at the level of 100 mg/l.