A study was conducted in El Salvador, Central America, to determine the rearing efficiency and rate of increase of a laboratory colony of Anopheles albimanus Wiedemann. An average of 6779 eggs per larval rearing tray produced 6250 larvae, 3822 pupae, and 3502 adults (1873 males and 1629 females). From each rearing tray, an average of 874 mosquitoes died as larvae and 1554 larvae were discarded after the third pupal separation. Adult females laid an average of 145 eggs each: therefore, 1629 females (the number produced per rearing tray) should produce a total of 236,205 eggs. A 34.8X rate of increase per generation occurred with this colony.