Background: Acute osteomyelitis and septic arthritis are most common acute infectious conditions of bone encountered at the emergency or outpatient department at hospitals. Both septic arthritis and osteomyelitis are threat for joint destruction, physeal damage and osteonecrosis, which warrants prompt and specific diagnosis and treatment. This study endeavours to evaluate Procalcitonin as diagnostic tool for earliest and specific diagnosis of acute bone and joint infection. Methods: This is a prospective type hospital based study conducted at a tertiary care hospital ,carried out between October 2015 to April 2017 which included total of 78 participants divided in two groups ,the cases and control group, each containing 39 patients. Clinical parameters as fever, pain, swelling and laboratory findings as Total Leucocyte Count(TLC), Erythrocyte Sedimentation Rate(ESR), C Reactive protein(CRP) and Procalcitonin(PCT) were measured. Baseline characteristic of the two groups compared. The sensitivity, specificity and p-values were compared using chi square and fisher's exact test, SPSS software version 20 used. Results: Total of 78 patients participated, 39 taken as cases and 39 as control. Out of 78 patients, males-48 (61.54%), and females-30(38.46%) with average age of participants as 23.5 years. ESR, CRP and TLC and procalcitonin was found to be elevated in all the cases .The P value for CRP and Procalcitonin was 0.00001 and significant correlation was observed between cases and PCT serum level. For septic arthritis the specificity of Procalcitonin came