1. The production of hatching eggs in tropical flocks of broiler breeders was estimated from records of initial body weight and subsequent body weight gains from 6 flocks containing over 140 000 birds in Venezuela using a stochastic model developed in temperate climates. The model was then modified to account for the greater persistency of egg production in the tropical environment of Venezuela. 2. The tropical model overestimated total egg production by 18 eggs. Lin's concordance correlation coefficient averaged 099 compared with 085 for the temperate model of egg production. 3. It was concluded that the modified model simulated egg production sufficiently well in the tropical environment to make it a useful management tool. Breeding company recommended target rates of lay for broiler breeders subjected to a long photoperiod during rearing such as in the tropics should be modified to account for their greater persistency of lay.