Introduction: Streptolysin “O” is a toxic immunogenic exoenzyme produced by haemolytic Streptococci of groups A, C and G. Measuring the ASO antibodies are useful for the diagnostic of rheumatoid fever, acute glomerulonephritis and streptococcal infection. Rheumatic fever is an inflammatory disease affecting connective tissue from several parts of human body as skin, heart, joints etc. and acute glomerulonephritis is a renal infection that affects mainly to renal glomerulus. Principle: The ASO-Latex is a slide agglutination test for the qualitative and semi-quantitative detection of anti-steptolysin “O” (ASO) antibodies. Latex particles coated with steptolysin “O” are agglutinated when mixed with samples containing ASO.