Objective: Emergency departments are resource-intensive environments in which diagnostic testing accounts for a significant share of overall healthcare spending. Inadequate physician awareness of the costs associated with these tests has been associated with unnecessary utilization and increased strain on healthcare systems. This study assessed Emergency Medicine (EM) residents in Türkiye regarding their knowledge and awareness of costs for commonly ordered laboratory and imaging tests.Materials and Methods: This prospective cross-sectional survey was conducted among EM residents across Türkiye. A 35-item questionnaire evaluated demographics, cost awareness, and estimation accuracy for 14 diagnostic tests. Estimates within ±25% of actual costs per the national Public Health Service Pricing Schedule were considered accurate, in accordance with thresholds used in prior studies assessing physicians’ awareness of medical costsResults: A total of 270 residents participated (mean age 29.6 ± 3.4 years; 65.2% male). Only 12.6% believed they had sufficient knowledge, and 2.6% had prior cost-related training. The mean accuracy across participants was 17.7% (95% CI: 16.6%-18.9%), with no test accurately estimated by more than one-third of participants. The highest accuracies were observed for serum β-hCG (30.7%), abdominal ultrasound (26.3%), and blood gas analysis (23.3%). Laboratory tests like troponin (50.0%) and blood gas (47.0%) were mostly underestimated, whereas β-hCG (40.0%) and diffusion MRI (34.4%) were overestimated. Over half (56%) reported ordering unnecessary tests. Subgroup analyses showed no significant differences in accuracy by gender, hospital type, or experience.Conclusion: EM residents in Türkiye show limited knowledge and low accuracy in estimating diagnostic test costs. The very low rate of prior education and high demand for training indicate a critical gap in medical curricula that should be addressed to reduce unnecessary testing and healthcare costs.