Titan broiler chickens kept in batteries at the Universidad Agraria, Lima, were fed diets containing duckweed (Lemna gibba) in proportions of 0, 10, 15 and 25%. The weight gain of broilers fed 15% duckweed was similar to that of the controls; 25% duckweed in the diet resulted in a significant decrease in feed consumption and weight gain. To determine if Titan and Arbor Acres broiler chickens could be maintained on duckweed diets under commercial conditions, birds were fed diets containing 0 and 5% duckweed. Female birds (Titan and Arbor Acres) fed diets containing 5% duckweed showed increased final weights. The pigmentation of all birds receiving the diet containing duckweed was significantly increased. Duckweed used at levels of up to 15 % in the diets of broiler chickens could represent an important protein source for poultry feed in developing countries where soyabean meal or fish-meal are not available. © 1994, Cambridge University Press. All rights reserved.