Ultrasonic nebulization applied to atomic absorption spectrometry gives a sensitivity ten to twenty times better than that which can be obtained by classical pneumatic nebulization. This gain in sensitivity is primarily due to the quantity of aerosol introduced into the flame, but is equally due to the fineness of the droplets that are formed. The study of certain parameters (frequency, power applied to the emitter, geometry of the nebulizing chamber, gas flow) has led to the specification of an ultrasonic nebulizer that can be conveniently used for routine analyses.