Introduction: Streptococcus pyogens is the commonest human pathogen causing widespread infections. Streptococcal antibody tests like the antistreptolysin O titre (ASO), the antideoxyribonuclease-B titre (anti-DNAase-B, or ADB) and the streptozyme test can be used for diagnosis of streptococcal infections. ASO test is done using latex agglutination method. Aim: To detect prevalence of anti-streptolysin O (ASO) antibodies in serum samples received in microbiology laboratory from patients of suspected streptococcal infections. Material and Methods: This study was conducted in serology section of Microbiology laboratory, Sir Takhtsinhji Hospital, Bhavnagar between the periods of June 2019 to October 2020. Serum samples received in serology section of microbiology requested for Anti streptolysin O test were tested by ASO- latex slide agglutination test by Pathozyme Diagnostics. Total 476 serum samples were tested. The results were recorded and analysed for the study. Results: Total prevalence for ASO positive serum samples were 46(9.8%), the highest prevalence 15% found in age group of 0-20 years. Conclusion: For detecting antecedent streptococcal infection the estimation of ASO antibodies is a simple, cost effective way. The increased level of ASO can support the diagnosis of rheumatic fever. ASO prevalence was found to be highest in the 0-20 year’s age group.