Ethical considerations can prohibit the use of traditional unconditional stimuli (USs), such as electric shocks or loud tones, when children or adolescents participate in aversive Pavlovian conditioning experiments. The present study evaluated whether an unpleasant sound provides a viable alternative. Fifteen boys and girls aged 13 to 17 years completed a differential Pavlovian conditioning procedure in which a conditional stimulus (CS) was followed by the sound of metal scraping on slate. Acquisition of conditioned responses was found in startle blink magnitude, expectancy judgments of the sound, and skin conductance responses. Extinction of conditioned responses was found in all measures when the CS was no longer followed by the unpleasant sound. Subjective ratings and skin conductance responses indicated that the sound was unpleasant because of its qualitative features, rather than its intensity. The results support the use of an unpleasant sound as a low-risk alternative to traditional USs in aversive Pavlovian conditioning experiments with children and adolescents.