Meningococcal disease has been a serious public health problem in the city of Rio de Janeiro, with high attack rates among younger children, high case fatality rates, and predominance of serogroup B. In December 1994 the second vaccination drive against B and C meningococcal disease was performed with the objective of protecting children ages 6 months to 13 years. A total of 950 thousand children received 2 doses of vaccine produced by the Finlay Institute of Cuba. In 1995 a change was observed in the disease pattern with a predominance of serogroup C and a higher global attack rate, particularly among children under 1 year of age, teenagers, and young adults. In vaccinated groups the attack rate was lower than in 1994, due to a decrease in serogroup B. No change was observed in the case fatality rate.