• Physical Examination, Weight, ECOG Performance Status, Hematology, Serum Chemistry & tumor markers before each cycle & end of study
  
• Toxicity Assessment & Concomitant Medications Continuously during treatment & end of study
  
• Diagnostic Imaging for Tumor Assessment & Quality of life (QOL) forms Every 6 weeks/ 3 cycles & end of study.
  

Inclusion Criteria:

1. Age >/= 18 years old.
2. Signed informed consent/authorization is obtained prior to conducting any study-specific screening procedures.
3. Patients should fulfill the criteria for UPC: no primary detected after a complete evaluation which is defined as complete history and physical, detailed laboratory examination, directed radiologic studies, symptom or sign directed invasive studies, directed immunohistochemistry studies and serum tumor markers.
4. Previously untreated or has received no more than one prior chemotherapy regimen for unknown primary cancer. If the patients are previously treated, they may not have had previous exposure to gemcitabine or oxaliplatin. Prior exposure to cisplatin or carboplatin is allowed for this study.
5. ECOG performance status must be 0-2 (Appendix A).
6. Adequate hepatic, renal and bone marrow function: Leukocytes >= 3,000/uL; Absolute neutrophil count >= 1,500/uL; Platelets >= 100,000/uL; Total bilirubin <= 1.5 X institutional upper limits of normal (ULN); AST (SGOT)/ALT (SGPT) <= 2.5 X institutional ULN; Creatinine <= 1.5 mg/dL.
7. Women of childbearing potential are not excluded from this study; however all participants (men and women) with reproductive potential must practice an effective method of contraception while on this study in order to minimize risks to fetuses.
8. Patients may have received prior radiation treatment but the last fraction of radiation treatment must have been completed at least 4 weeks prior to entry on this study.
9. Patients must have at least one measurable lesion as per the RECIST Criteria that can be accurately measured in at least one dimension, with minimum lesion size equal to or more than twice the thickness of the imaging study used. If radiation was previously received, measurable disease must occur outside the previous radiation field, unless disease progression has been documented.
10. Both men and women and members of all ethnic groups are eligible for this trial.

Exclusion Criteria:

1. In previously treated patients; patients should not have received gemcitabine or oxaliplatin as one of the agents.
2. Uncontrolled intercurrent illness including, but not limited to, active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmias not well controlled with medication, myocardial infarction within the previous 6 months, or psychiatric illness/social situations that would limit compliance with study requirements.
3. Patients with known brain metastases should be excluded from this clinical trial because of their poor prognosis and because they often develop progressive neurological dysfunction that would confound the evaluation of neurological and other adverse events. A CT scan of the brain is not needed for eligibility and will be done only if the patient presents with symptoms suggestive of brain metastases.
4. Patients who have had chemotherapy within 4 weeks (6 weeks for nitrosoureas or mitomycin C) prior to entering the study or those who have not recovered from adverse events due to agents administered more than 28 days earlier.
5. Patients may not be receiving any other investigational agents, or have participated in any investigational drug study within 28 days preceding start of study treatment.
6. The teratogenic potential of this combination is currently unknown. Women who are pregnant or lactating are excluded.
7. History of any other malignancy in the last 5 years, except patients with a prior history of in situ cancer or basal or squamous cell skin cancer are eligible.
8. Peripheral neuropathy > grade 1.
9. Female patients with adenocarcinoma with axillary only nodes will be excluded from the study.