: Between 1987-88 and 1989-90, 18 Sarus cranes (Grus antigone), more than 50 collared doves (Streptopelia decaocto) and a few blue rock pigeons (Columba livia) were found dead during winter in Keoladeo National Park, Bharatpur, which coincided with the application of aldrin in the crop fields around the Park. Brain tissue of Sarus cranes, collared doves and blue rock pigeons contained an average of 19.33 (3.56-43.46), 15.19 (7.40-20.70), and 20.42 (14.61-26.23) ppm, wet weight, of dieldrin, respectively. Dieldrin in other tissues ranged from 0.78 ppm to 92.26 ppm in Sarus cranes, 3.44 ppm to 66.17 ppm in collared doves and 16.92 ppm to 20.99 ppm in blue rock pigeons. Residues of aldrin were as high as 89.75 ppm in the gastrointestinal tract of a Sarus crane and 104.00 ppm in a collared dove. Very high residues of aldrin in the gastrointestinal tract, and dieldrin at much higher quantities in the brain than the lethal level (4-5 ppm) clearly indicate that dieldrin, after being metabolized from aldrin, was responsible for the deaths. A decline in the breeding population of Sarus cranes in Keoladeo National Park has been noticed, and is suspected to be an indication of its general population trend. The Registration Committee under the Indian Insecticide Act of 1968 has decided to include aldrin in the banned list with the ban taking effect from January 1994.