Strontium showed a high atomic emission in a molybdenum microtube. The addition of hydrogen in the argon gas atmosphere served to increase the atomic emission. No interferences from less than 5 ng of potassium, calcium and magnesium were found. Other elements also had no interferences at the concentration levels usually found in biological samples. Samples were digested with nitric acid in a Uni-Seal decomposition vessel. The results obtained showed good agreement with the certified values. Atomic emission spectrometry with a molybdenum microtube atomizer permits a simple and sensitive determination of strontium in biological samples (coefficient of variation 2.5% for 10 pg Sr).