Immune Response & Safety Comparison of 3 Lots of GSK Biologicals' DTaP-IPV Candidate Vaccine to DTaP + IPV Vaccine.

- Investigational groups: 3, each receive one of 3 lots of DTaP-IPV vaccine.

- Control: US-licensed DTaP (Infanrix) + US-licensed IPV (IPOL) vaccines administered in
separate injections.

- Two study visits one month apart for a subset of subjects (Safety and Immunogenicity
subset) with a blood draw at each visit. All other subjects will have one visit.

- A telephone contact 4-6 days after vaccination for all subjects, a telephone contact
31-38 days after vaccination for the Safety only subset and a telephone contact for all
subjects during the extended safety follow-up phase (5 months following the active
phase).

Inclusion Criteria:

- Healthy male or female child between and including 4 and 6 years of age at the time of
vaccination.

- Subjects should have received 4 doses of GSK DTaP (primary vaccination course with
booster dose in the second year of life) and 3 doses of IPV during the first 2 years
of life and vaccination against measles, mumps, and rubella in the second year of
life.

Exclusion Criteria:

- Use of any investigational or non-registered drug or vaccine other than the study
vaccines within 30 days preceding the administration of study vaccines, or planned use
during the study period.

- Administration or planned administration of a vaccine not foreseen by the study
protocol within 30 days of study vaccination and ending at Day 30.

- Chronic administration or planned administration of immunosuppressants or other immune
modifying drugs within six months prior to study vaccination or planned administration
during the study period.

- Administration of immunoglobulins and/or blood products within 3 months prior to
vaccination or planned administration during the study period.