Inclusion Criteria:  Females aged between 20-60 years old. Preoperative physical status: ASA (American Society of Anesthesiology) I & II. Body mass index (BMI) < 35 Kg/ m2. Candidate for unilateral modified radical mastectomy. Informed consent to participate in the study.  Exclusion Criteria:  - Females aged < 20 years old or > 60 years old. Preoperative physical status: ASA III & IV. Morbid obese patients with BMI > 35 Kg/ m2. Refusal to participate in the study. Addiction to narcotics or psycho-active drugs. Psychological disorders. Contra-indications to regional anesthesia (coagulopathy, injection site infection or allergy to any of the study drugs)