Mastitis is recognized as one of the most important diseases affecting dairy animals resulting in sub-stantial economic losses worldwide due to reduced milk production and quality. The present study was designed to evaluate the effect of antibiotic treatment and Priplasmic membrane protein (PMP) on mastitis and immunomodulating effect in mastitic dairy goats. The experiment was carried out on 10 lactating goats suffered from mastitis that were divided into two groups. The first group was treated by the antibiotic of choice only and the second group was treated by antibiotic and PMP. A number of 10 milk samples were collected from examined mastitic dairy goats and examined for SCC, TBC, isolates identification, antibiotic sensitivity test Nitric oxide level and Lysozyme level before & after treatment). Coagulae negative Staph, S. aureus, Coliform and St. dysagalactia were isolated in percentage 100%, 80%, 70% and 50%, respectively. Amoxicillin + Clavulinic Acid is the drug of the choice according to the sensitivity test. After treatment by antibiotic and PMP, TBC & SCC were decreased more than the treatment by antibiotic only. Meanwhile, immunostimulating parameter (Nitric oxide & Lysozyme) were increased. Therefore, the current work point out that the concurrent administration of biological preparation (PMP) with therapeutic drug (Synulox® ) improve the immune response ( nitric oxide and lysozyme activity ) in treated goats.