Introduction:During preoperative preparation, patients undergo investigations to detect asymptomatic diseases. The probability of finding significant abnormalities on such routine investigations is small, and these investigations unnecessarily increase costs of perioperative care. We evaluated current practices, compliance with national guidelines and costs of preoperative investigations at the National Hospital of Sri Lanka (NHSL).Materials and Methods:Patients undergoing elective surgery at the general surgical units of the NHSL from June to August 2010 were included in this study. The National Guidelines on Preoperative Investigations were the standard of assessment. Data on preoperative investigations were collected using an expert-validated pretested interviewer-administered questionnaire.Results:Sample size was 2,061 patients. Mean age of the patients was 46.7±15.8 years; males constituted 54.2% of the study population. Majority of the patients were ASA-I (68.5%) and surgical grade II (62.0%). Request for chest X-ray and prothrombin time / international normalized ratio least conformed to the guidelines. Only fasting blood sugar / random blood sugar demonstrated ‘good’ compliance (>70%) to the guidelines. An ‘acceptable’ compliance (50%-70%) was seen for electrocardiogram, blood grouping and full blood count. All other investigations demonstrated ‘poor’ compliance (<50%) with the guidelines. The total excess cost incurred due to non-recommended investigations during the study period of 3 months was Sri Lankan Rupees (LKR.) 1,324,860 to 2,044,210 (per patient LKR. 642.82-991.85). Intern house officers (IHOs) were involved in the planning of preoperative investigations in 2,001 patients (97.1%), followed by medical officeranesthesia / registrar-anesthesia (n=1,625; 78.8%), surgical registrars (n=190; 9.2%), consultant (n=70; 3.4%), senior registrar (n=46; 2.2%) and senior house officers (n=22; 1.1%). Non-recommended investigations were requested mostly by the IHOs and medical officer–anesthesia / registrar-anesthesia.Conclusions:Unnecessary preoperative investigations are common at our institution, leading to substantially excessive costs. There is ample opportunity to rationalize practices and reduce expenditure.