Inclusion Criteria:

- Histologic or cytologic diagnosis of unresectable nonsquamous Stage IIIA or Stage
IIIB (without malignant pleural/pericardial effusions) NSCLC.

- Have an Eastern Cooperative Oncology Group Performance Status of 0 or 1.

- Previous radiation therapy should have been limited and must not have included
thoracic radiation, whole pelvis radiation, or radiation to >25% of the patient's
bone marrow, patients must have recovered from the toxic effects of radiation
treatment prior to study enrollment (except for alopecia). Prior radiotherapy must be
completed 30 days before study entry.

- Have at least 1 unidimensionally measurable lesion meeting RECIST guidelines, version
1.0.

- Estimated life expectancy of at least 12 weeks.

- Patient compliance and geographic proximity that allow adequate follow-up.

- Adequate bone marrow reserve, hepatic-, renal- and pulmonary function.

- Patients must sign an Informed Consent Document.

- Patients must have a total lung V20 less than or equal to 35%.

- For women: Must be surgically sterile, postmenopausal, or compliant with a medically
approved contraceptive regimen, during and for 6 months after the treatment period;
must have a negative serum pregnancy test within 7 days before study enrollment and
must not be breast-feeding. For men: Must be surgically sterile or compliant with a
contraceptive regimen during and for 6 months after the treatment period.

- Have not received prior systemic anticancer therapy for NSCLC.

Exclusion Criteria:

- Have received treatment within the last 30 days of enrollment with a drug that has
not received regulatory approval for any indication at the time of study entry.

- Have previously completed or withdrawn from this study or any other study
investigating pemetrexed.

- Have a serious concomitant systemic disorder that, in the opinion of the
investigator, would compromise the patient's ability to adhere to the protocol.

- Have a serious cardiac condition, such as myocardial infarction within 6 months,
angina, or heart disease, as defined by the New York Heart Association Class III or
IV.

- Have had a prior malignancy other than NSCLC, carcinoma in situ of the cervix, or
non-melanoma skin cancer, unless that prior malignancy was diagnosed and definitively
treated at least 5 years previously with no subsequent evidence of recurrence.
Patients with a history of low-grade (Gleason score less than or equal to 6)
localized prostate cancer will be eligible even if diagnosed less than 5 years
previously.

- Are receiving concurrent administration of any other antitumor therapy.

- Have had weight loss of more than 10% over the previous 3 months before study entry.

- Are unable to interrupt aspirin or other non-steroidal anti-inflammatory drugs
(NSAIDs), other than an aspirin dose less than or equal to 1.3 grams per day, for at
least 2 days before (5 days for long-acting agents), the day of, and for at least 2
days after administration of pemetrexed.

- Are unable or unwilling to take folic acid or vitamin B12 supplementation.

- Are unable or unwilling to take corticosteroids.

- Have received a recent yellow fever vaccination (within 30 days of enrollment) or are
receiving concurrent yellow fever vaccination.

- Have known hypersensitivity to pemetrexed, cisplatin, or any of the excipients in
these medicinal products.

- Have evidence of clinical hearing loss.

- Have clinically significant third-space fluid collections, that cannot be controlled
by drainage or other procedures prior to study entry.