Inclusion Criteria:

• Patients must have microscopically confirmed head and neck squamous cell carcinoma (HNSCC), recurrent and/or metastatic.
• Confirmation of HNSCC may be obtained from the primary site or metastatic disease.
• Patients must be at least 18 years of age.
• Karnofsky Performance status must be ≥ 70%.
• Disease must be measurable by RECIST criteria.
• At least 6 weeks must have elapsed from previous radiation therapy. Patient must have recovered from the acute toxic effects of treatment prior to study enrollment.
• Adequate organ function, as follows:
• Adequate bone marrow reserve: absolute neutrophil count (ANC) ≥ 1.5 X 109/L, platelets ≥ 100 X 109/L, and hemoglobin ≥ 9 g/dL.
• Hepatic: total bilirubin within normal limits (≤ 1.0 mg/dL); alkaline phosphatase (AP), aspartate transaminase (AST) and alanine transaminase (ALT) ≤ 1.5 X ULN (upper limit of normal)
• Renal: Serum creatinine ≤ 1.3 mg/dL. Patients with serum creatinine > 1.3 mg/dL may be eligible if creatinine clearance (CrCl) ≥ 45 mL/min based on the standard Cockroft and Gault formula.
• Patients of childbearing potential must have a negative serum pregnancy test within 14 days of treatment. Patients must agree to use a reliable method of birth control during and for 3 months following the last dose of study drug.
• Patients must sign an informed consent document.

Exclusion Criteria:

• Previous exposure to temsirolimus or other mTOR inhibitors
• More than 2 prior cytotoxic regimens in the recurrent/metastatic disease setting
• History of any brain metastases
• Patients who require concomitant medications that are metabolized by hepatic CYP3A4, due to potential drug-drug interaction with temsirolimus
• Patients with known active interstitial pneumonitis
• Active infection or serious underlying medical condition that would impair the patient's ability to receive protocol treatment.
• Women who are pregnant or lactating
• Other active malignancy, other than indolent malignancies which the investigator determines are unlikely to interfere with treatment and safety analysis
• Patients with multifocal peripheral sensory alterations or paresthesias (including tingling) interfering with function, per patient report (example: activities of daily living)
• Therapeutic anticoagulation with Coumadin (warfarin)
• Hypertriglyceridemia ≥ grade 2 (CTCAE version 3.0).
• Impaired lung function: O2 saturation 88% or less at rest on room air by Pulse Oximetry. If O2 saturation is ≤ 88% at rest, further pulmonary function tests (PFTs) should be ordered to confirm normal pulmonary function and eligibility.