Inclusion Criteria:

• Signed Written Informed Consent
• Histologically confirmed Stage III (unresectable) or Stage IV melanoma
• Must have failed at least one systemic therapy for malignant melanoma or be intolerant to at least one prior systemic treatment. Note: Enrollees must not be eligible for a clinical study with Ipilimumab
• Subjects with asymptomatic brain metastases are eligible
• Primary ocular and mucosal melanomas are allowed
• Must be at least 28 days since treatment with chemotherapy, biochemotherapy, or immunotherapy, and recovered from any clinically significant toxicity experienced during treatment. Must have recovered from prior surgery or radiation. Systemic corticosteroids should be eliminated or weaned to the minimum dose before starting Ipilimumab treatment. Consult with the Medical Monitor for individual subjects
• Eastern Cooperative Oncology Group (ECOG) performance status (PS) 0- 2
• Life expectancy ≥ 16 weeks
• Subjects must have the complete set of baseline (screening/baseline) radiographic images, including but not limited to brain, chest, abdomen, pelvis, and bone scans

• Required values for initial laboratory tests:

  1. White Blood Cells (WBC): ≥ 2000/uL (≥ 2 x 10*9*/L)
  2. Antigen Neutrophil Count (ANC): ≥ 1000/uL (≥ 1 x 10*9*/L)
  3. Platelets: ≥ 75 x 103/uL (≥ 75 x 10*9*/L)
  4. Hemoglobin: ≥ 9 g/dL (≥ 80 g/L; may be transfused)
  5. Creatinine: ≤ 2.0 x ULN
• Aspartate Aminotransferase (AST)/Alanine Aminotransferase (ALT):≤ 2.5 x Upper Limit of Normal (ULN) for subjects without liver metastasis ≤ 5 times for liver metastases
• Bilirubin: ≤ 2.0 x ULN (except for subjects with Gilbert's Syndrome, who must have a total bilirubin of less than 3.0 mg/dL)
• Men and women, at least 16 years of age
• Prior treatment with an anti-Cytotoxic T-lymphocyte Associated Protein 4 (CTLA-4) drug is allowed provided therapy was not discontinued to to drug-related toxicity

Exclusion Criteria:

• Women of Child-Bearing Potential (WOCBP) who are unwilling or unable to use an acceptable method to avoid pregnancy for the entire study and for up to 8 weeks after the last dose of investigational product
• WOCBP using a prohibited contraceptive method
• Women who are pregnant or breastfeeding
• Women with a positive pregnancy test on enrollment or before investigational product administration
• Subjects on any other systemic therapy for cancer, including any other experimental treatment
• Prior treatment with an anti CTLA 4 antibody if treatment failure was due to Immune-Related Adverse Events (irAEs) or discontinuation was due to an Adverse Event (AE)/Serious Adverse Event (SAE)
• Any subject enrolled in a registrational study (ie, CA184024) that has a survival endpoint should not be enrolled in CA184-045. Also, if a subject is eligible for a treatment study, he or she is not eligible for this study
• Presence of active autoimmune disease
• Presence of known hepatitis B or hepatitis C (active) infection, regardless of control on antiviral therapy
• Any subject who has a life threatening condition that requires high-dose immunosuppressants
• Subjects with melanoma who have another active, concurrent, malignant disease, with the exception of adequately treated basal or squamous cell skin cancer, superficial bladder cancer, or carcinoma in situ of the cervix
• Any non-oncology vaccine therapy used for prevention of infectious diseases for up to 4 weeks before or after any dose of Ipilimumab, with the exceptions of Amantadine and Flumadine
• Any subject enrolled in a registrational study (ie, CA184-024) that has a survival as a primary endpoint should not be enrolled in CA184-045. Also, if a subject is eligible for a treatment study, he or she is not eligible for this study