Inclusion Criteria:

• Histologic or cytologic diagnosis of NSCLC
• Presence of Stage IIIB or Stage IV disease
• Patients must have received no prior systemic chemotherapy
• Patients must have at least one bi-dimensionally measurable lesion with clearly defined margins and two perpendicular diameters that are clearly measurable by any of the following: chest x-ray, with at least one diameter 1.0 cm or greater, CT, with both diameters greater than the distance between cuts of the imaging study, palpation, with both diameters 2.0 cm or greater, or disease progressing in areas of prior radiation therapy may be included
• No prior radiotherapy for the target organ, no other radiotherapy for at least 2 weeks prior to study enrollment and the patient must have fully recovered from all acute toxic effects of the treatment.

Exclusion Criteria:

• Are investigator site personnel directly affiliated with the study, or are immediate family of investigator site personnel directly affiliated with the study. Immediate family is defined as a spouse, parent, child, or sibling, whether biological or legally adopted.
• Are employed by Lilly (that is, employees, temporary contract workers, or designees responsible for the conduct the study). Immediate family of Lilly employees may participate in Lilly sponsored clinical trials, but are not permitted to participate at a Lilly facility. Immediate family is defined as a spouse, parent, child, or sibling, whether biological or legally adopted.
• Have received treatment within the last 30 days 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• Have previously completed or withdrawn from this study or any other study investigating gemcitabine.