OBJECTIVES: To determine whether, for symptomatic urolithiasis, the thresholds to intervene and the nature of the intervention might be susceptible to practice style differences that vary by day of presentation. Weekend hospital admission is associated with different and poorer quality care in certain clinical settings. METHODS: Using the Florida State Inpatient Database for 2005, we identified admissions (n = 8589) for symptomatic urolithiasis using the "International Classification of Diseases, 9th revision" diagnosis codes. A multiple logistic regression model was fit, measuring the association between weekend admission and surgical intervention, controlling for patient differences. Among the surgically treated patients, the relationship between weekend admission and the likelihood of having definitive (vs temporizing) surgery was measured. RESULTS: Weekend admission was associated with a lower likelihood of surgery (odds ratio 0.88, 95% confidence interval 0.80-0.97). Patients with complicating factors, such as fever, were more likely to undergo surgery than those without such characteristics (adjusted odds ratio 1.28, 95% confidence interval 1.16-1.41). However, when surgery was performed, the use of definitive surgery was similar between the patients admitted on the weekend and those admitted on weekdays (adjusted odds ratio 1.02, 95% confidence interval 0.90-1.17). CONCLUSIONS: Patients with symptomatic urolithiasis who are admitted on the weekend are less likely to undergo surgery than those admitted during the week. However, the likelihood of intervention was similar among the patients with complicating factors. Physicians appear to treat the sickest patients the same, regardless of weekend admission; more elective surgical care may occur during the week.