Inclusion Criteria:

• Subjects who the investigator believes that their parents/guardians can and will comply with the requirements of the protocol (e.g. completion of the diary cards, return for follow-up visits) should be enrolled in the study.
• A male or female between, and including, 11 and 21 months of age (e.g. from age 11months until the day before age 22 months) at the time of the first vaccination.
• Written informed consent obtained from the parent or guardian of the subject after they have been advised on the risks and benefits of the study in a language they clearly understand, and before performance of any study procedure.
• Free of obvious healthy problems as established by medical history and clinical examination before entering into the study.

Exclusion Criteria:

• Use of any investigational or non-registered product (drug or vaccine) other than the study vaccine(s) within 30 days preceding the first dose of study vaccine, or planned use during the study period.
• Chronic administration (defined as more than 14 days) of immunosuppressants or other immune-modifying drugs within six months prior to the first vaccine dose.
• Administration of immunoglobulins and/or any blood products during the six months before entering the study or planned administration during the study period.
• Planned administration/ administration of a vaccine not foreseen by the study protocol within 30 days prior to until 42 days after each study vaccine dose with the exception of oral polio vaccine (OPV) which can be given at any time and routine inactivated vaccines such as pneumococcal, meningococcal or Haemophilus influenzae type b conjugate vaccines, inactivated influenza or diphtheria/tetanus containing vaccines which can be administered up to eight days before each study vaccine dose.
• Previous vaccination against measles, mumps, rubella and/or varicella.
• History of measles, mumps, rubella and/or varicella/zoster diseases.
• Known exposure to measles, mumps, rubella and/or varicella within 30 days prior to study start.
• Any confirmed or suspected immunosuppressive or immunodeficient condition, including human immunodeficiency virus (HIV) infection.
• A family history of congenital or hereditary immunodeficiency.
• History of allergic disease or reactions likely to be exacerbated by any component of the vaccine(s), including systemic hypersensitivity to neomycin.
• Major congenital defects or serious chronic illness.
• History of any neurologic disorders or seizures.
• Acute disease at the time of enrolment.
• Rectal temperature ≥38°C or axillary temperature >=37.5°C at the time of vaccination.
• Residence in the same household as a high risk person e.g.:
• New-born infants (0-4 weeks of age)
• Pregnant women who have a negative history of chickenpox
• Persons with known immunodeficiency