Background and Aims: Preoperative laboratory testing is done to detect abnormalities in the body not detected by clinical examination. Often a battery of tests is advocated as a routine for patients scheduled for low or intermediate risk surgery. This prospective observational study was aimed to assess agreement of the current practice of preoperative laboratory investigations with the National Institute of Clinical Excellence (NICE) guidelines, and the impact of investigations on patient care and costs. Material and Methods: The study was conducted at a tertiary referral center on 385 patients aged 18-70 years of either gender, posted for elective general surgical, gynaecological or otolaryngological surgery. Sixteen investigations were examined: hemogram, blood urea, serum creatinine, serum electrolytes, coagulation profile, urinalysis, thyroid function tests, electrocardiogram, echocardiogram, chest x-ray, pulmonary function tests, blood sugar, glycosylated hemoglobin, liver function tests, treadmill test and coronary angiogram. The history and physical examination were reviewed to examine for indication for these laboratory investigations. These were compared with NICE guidelines. Impact of these investigations on anesthetic decision-making was noted. Results: There was almost no agreement of the current practice with the NICE guidelines. The total cost of all tests obtained was Rs 5,48,755. Total additional cost of unindicated tests was Rs 5,10,730 (93%). Average amount spent on additional investigations per patient was Rs 1326.57. Conclusion: Most investigations are overprescribed and have minimal agreement with NICE guidelines. None of the tests had any impact on clinical care. Nearly a million rupees is incurred per year in one referral hospital alone, when NICE guidelines are not followed.