Pain is one of the most misunderstood, underdiagnosed, and untreated medical problems, particularly in children. New Joint Commission on Accreditation of Health Care Organization regards pain as fifth vital sign and requires caregivers to regularly assess pain. Inadequate pain relief during childhood may have long-term negative effects including harmful neuroendocrine responses disrupted eating and sleep cycles and increased pain perception during subsequent painful experiences. Also, postoperative pain can result in an uncooperative and restless child. Hence, it is preferable to prevent the onset of pain rather than to relieve its existence.

Various multimodal techniques have been designed for pediatric pain relief. These include both systemic and regional analgesia. The most commonly used regional technique is caudal epidural block. Advantages of the caudal block are smoother recovery with less distress behavior, early ambulation, decreased the risk of chest infections, decreased postoperative analgesic requirements, and early discharge.

In our culture; considerable number of parents still refuses caudal anesthesia fearing from the rare neurological sequelae may occur. This the motive for searching for parenteral surrogate gives clear headed recovery resembles regional analgesia.

Dexmedetomidine is an alpha 2 agonist which has sedative, analgesic, and opioid-sparing effect. It prolongs the duration of analgesia by its local vasoconstrictive effect and by increasing the potassium conductance in A-delta and C-fibers.

It also exerts its analgesic action centrally via systemic absorption or by diffusion into the cerebrospinal fluid and reaches alpha 2 receptors in the superficial laminae of the spinal cord and brainstem or indirectly activating spinal cholinergic neurons. The sedative effects of dexmedetomidine are mostly due to stimulation of the alpha 2 adrenoceptor in the locus coeruleus

Inclusion Criteria:

1. male children
2. american society of aneasthesia physical status grade I &II
3. patients aged from 2 years to 12 years
4. patients will undergoing hypospadias repair surgery

Exclusion Criteria:

1. history or evidence of infection at the back
2. allergy to the study drugs
3. bleeding/coagulation disorder
4. developmental delay
5. septic patients
6. neurological or spinal diseases.