This 4 arm study will assess the optimal starting dose of Mircera in the treatment of anemia in patients with non-small cell lung cancer receiving first line myelosuppressive chemotherapy. Patients will be randomized to receive either Mircera 6.3 micrograms/kg, 9 micrograms/kg or 12 micrograms/kg s.c. every 3 weeks or darbepoetin alfa according to the approved local label (either 6.75 micrograms/kg s.c. every 3 weeks, or 2.25 micrograms/kg every week). The anticipated time on study treatment is <3 months and the target sample size is 100-500 individuals.

Inclusion Criteria:

• >=18 years of age;
• stage III or IV non-small cell lung cancer receiving first line myelosuppressive chemotherapy;
• myelosuppressive chemotherapy scheduled for at least 9 weeks;
• anemia at screening visit.

Exclusion Criteria:

• transfusion of red blood cells during the 4 weeks prior to first planned dose of study medication;
• iron deficiency anemia, or anemia caused by gastrointestinal bleeding;
• prior treatment with Mircera.