Monitoring in the practice of anesthesia is becoming increasingly sophisticated and complex, but the vigilance of the individual anesthesiologist remains the most important element in the safe conduct of anesthesia.Invasive monitoring in anesthesia practice has become synonymous with the observation of cardiovascular variables. Medical and technical knowledge of invasive monitoring is rapidly expanding, with manufacturers being quick to correct equipment problems as they are identified (for both commercial and legal reasons). Many companies also provide customdesigned products for individual hospitals (though we believe it would be improper to describe or compare the products of individual manufacturers). This chapter describes the application of currently available monitoring materials and techniques to pediatric practice.