Laboratory investigations are an important and reliable tool for proper diagnosis and treatment, carried out to confirm the findings or to estimate the etiology. Effective use of clinicians and the clinical laboratory has great implications on the cost and operational efficiency of the hospital. This study aimed to determine the diagnostic yield of certain routine clinical biochemical investigations in a rural teaching Hospital which was conducted in the central lab of the Department of the Biochemistry, Adesh Medical College and Hospital, Mohri, shahbad (M), Haryana. Out of 15 types of clinical biochemical investigations ordered, 11 types of tests were found to be in between 17% to 29 % diagnostic yield (low yield). Only four types of investigations were found to be in intermediate diagnostic yield percent in which Na⁺ has highest (41.2%) yield percent. The overall/average yield percent was found to be 27.7%. So, the laboratory investigations do assist a clinician in proper diagnosis, treatment and prevention of any illness or complications arising out of it. But unnecessary investigations must be ruled out in order to reduce the expenditure, man power and machinery damage due to overload.