In 2004, concurrent measles and rubella outbreaks occurred in four camps hosting 2767 Liberian refugees in Côte d'Ivoire. Sixty rash and fever cases were identified. From 19 January to 23 February 2004 (weeks 8-13), measles IgM testing showed that 61.1% were positive. The highest incidence rate (18.5%) of measles was observed in children aged <9 months. Ninety-three percent of children aged between 6 months and 15 years received a measles vaccine during week 13, but the rash and fever cases continued to occur. This prompted a systematic test for both measles and rubella IgM antibodies. Rubella IgM testing revealed 74.0% positive cases between 14 February and 25 April (weeks 11-21). The highest incidence rate (3.88%) of rubella was found in children aged between 5 and 15 years. Supplemental immunization with a measles-mumps-rubella (MMR) vaccine was conducted during week 20. This study illustrates the importance of testing for both measles and rubella in outbreaks of rash and fever in refugee settings.