Ages of grass carp ( Ctenopharyngodon idellus) larvae collected from Jiujiang section of the Yangtze River in 1998 , Shimatou and Shamao sections of the Yangtze River in 1999 , were determined by counting the increments in otolith. Birth date and daily growth rate of body length of the larvae were estimated based on the daily age. Average age of the larvae from Jiujiang , Shimatou and Shamao sections were 10. 7d , 8. 8 -16. 0d and 7. 0d , respectively. In the samples from Shimatou section , the age of larvae sampled on May 16 was older than that of the other samples. The average and specific growth rate of body length of the larvae from Shimatou section was 0. 11mm . d -1 and 1. 32 % , respectively. The correlation between body length and age was insignificant except in few samples , which suggested that the growth rate of larvae from the middle reaches of the Yangtze River was unequal , and some individuals might have suffered from the food absence.