Hyperhydricity is a physiological malformation in tissue culture generated plants that impedes acclimation to outdoor conditions during plant regeneration. Hyperhydrated plants are associated with low chlorophyll, low phenolics and high water content when compared to normal plants. In addition, hyperhydrated plants are morphologically characterized by translucent, enlarged, and brittle leaves and stems. Recently, a unique Pseudomonas sp. was used to prevent hyperhydricity in oregano shoot cultures. In this study three antibiotics, ampicillin, carbenicillin, and cefotaxime were tested to strengthen the findings that prevention of hyperhydration is a direct result of inoculation with Pseudomonas, and therefore its removal would reintroduce hyperhydricity in the plants. To determine hyperhydricity the water content, total free phenolics, and chlorophyll levels of oregano shoot clones were compared. Furthermore, the growth, vigour and survival rate of these shoot clones during regeneration in potted vermiculite were compared. Results show that water content and total free phenolics in antibiotic treated pre-inoculated clones reverted to levels present in hyperhydrated clones, while chlorophyll remained at the elevated levels found in untreated, pre-inoculated clones. The acclimation study showed that pre-inoculated clones not treated with antibiotics had the greatest growth, vigour and survival rate of any treatment.