Preoperative investigations are important elements of preoperative evaluation to determine the fitness for anaesthesia and surgery. [1,2,3].The objectives were to assess the number of unnecessary preoperative investigations carried out and repeated in Dental Hospital, Peradeniya and to analyze the cost of investigations that are performed unnecessarily. Reference guidelines were the NICE Preoperative Investigations Guideline (2016) [4] and the National Preoperative Investigations Guideline (2022) [5].The study was carried out on patients undergoing elective surgeries in the main theatre complex of Dental Hospital, Peradeniya, over a month. Pediatric surgeries, emergency surgeries, repeated surgeries and ICUbound patients undergoing surgeries were excluded.Forty-nine cases were performed during the study period (11 minor, 26 intermediates, and 12 major cases).According to the results; FBC- 15, BU-12, SCr- 20, SE (Na, K)- 25, SCl- 9, AST/ALT- 4, PT/INR- 9, CXR- 6, ECG- 11, 2D echocardiogram- 1, FBS/CRP- 1 were performed unnecessarily. The total unnecessary cost was 107,400 LKR over that month. This reveals an average of 2200 LKR unnecessary investigation costs per surgery. In conclusion, a considerable number of inappropriate investigations are performed in an elective preoperative setting which also has cost implications.