Objectives Between 2000 and 2006, 11 randomized controlled trials were published, demonstrating the efficacy of medical expulsive therapy (MET) for promoting upper tract stone passage. Although its use is gaining traction among urologists, they evaluate a minority of patients who present to the emergency department (ED) for acute renal colic before discharge. As such, measuring the uptake of MET into the broader medical community is important. Methods Data were analyzed (2000-2006) from the National Hospital Ambulatory Medical Care Survey. Sampled ED visits for stones were identified. The use of MET was ascertained by the prescription of a calcium channel or α blocker at the ED visit. National estimates of the prevalence of MET use were computed. Logistic regression was used to examine linear and nonlinear time trends in MET prescription. Results The use of MET increased throughout the study period. In fact, the odds of being treated with this approach more than doubled with each successive year (OR, 2.15; 95% CI, 1.31-3.5; P < .001 for the linear trend). However, the overall prevalence of use was exceedingly low at 1.1% (95% CI, 0.6%-1.9%). Given the number needed to treat of 4, this implies a missed opportunity to spare approximately 260 000 individuals annually from stone surgery and its risks. Conclusions Despite the growing body of evidence to support its safety and efficacy, our analysis reveals the sluggish dissemination of MET into the broader medical community. The observed underuse represents a block in the translation of clinical science into practice and raises a quality of care concern.