In this experiment, Robadiar (R) or Orego-Stim (OS) foreign commercial products were used as a source of oregano. A total number of 165 Inshas strain birds (150 hens and 15 cocks) 24-wks-old were used in this experiment up to 40 wks of age. All birds were individually weighed and randomly divided into 5 equal experimental groups (30 hens and 3 cocks of each) with three replicates (10 hens and 1 cock each) with almost similar initial average body weight. Replicates were randomly housed in floor pens. The first group was fed the basal diet without supplementation and served as control. The second and third groups were fed the basal diet supplemented with 0.2 and 0.4g Robadiar/kg diet, respectively as a first source of oregano. The fourth and fifth groups were fed the basal diet supplemented with 0.3 and 0.6g Orego-Stim/kg diet, respectively as a second source of oregano. The results obtained could be summarized as follows: hens fed diets supplemented with either R or OS as oregano recorded the best values of egg production percentage, egg mass and feed conversion ratio than the control group. Hens fed on 0.4g Robadiar/kg diet (T3) recorded the better feed conversion ratio compared with other treatments (except T2 group) or control groups. Improvement was found in yolk% in hens supplemented with T3 group compared with other treatments or control groups. Adding oregano at different levels and types to layer diets significantly (P≤0.05) increased relative oviduct, the highest values were recorded by T3 group. There were significantly (P≤0.05) decreased relative abdominal fat due to adding oregano to layer diets, the lowest value was recorded in the third group. Both total anaerobic and Escherichia coli (E. coli) counts of bacteria were significantly (P ≤ 0.05) decreased, while lactobacillus count was significantly (P ≤ 0.05) increased by different types of added oregano when compared to the control group. Birds of T3 group had recorded the lowest counts of both anaerobic and E. coli bacteria, and the highest count of lactobacillus compared to other treatments. Each of plasma total lipids, total cholesterol, Triglycerides, high density lipoproteins and low density lipoproteins concentrations were significantly (P≤0.05) decreased by all the dietary treatments compared to control group. While, concentrations of plasma proteins and plasma of aspartate amino transaminase and alanine transaminase activities were not affected.