The chapter commences with Qualitative determination of plasma proteins by immunoprecipitation. It discusses all related techniques – like – immunodiffusion, double diffusion, immunoelectrophoresis, electrophoresis, protein stains. A detailed presentation on Fundamental Quantitative Considerations is given which is followed by an exhaustive presentation on Turbidimetry. This technique is presented in detail along with the following parameters - RF, ASO, CRP. CRP-US, Microalbumin, IgG, IgM, IgA, IgE, C3, C4, Antithrombin III, Apo A1, Apo B, Lp(a), Beta 2 macroglobulin, Ceruloplasmin, Haptoglobin, Fibrinogen. Also mentioned are all about disorders as related to the above mentioned parameters. The chapter presents a detailed write up on Myocardial infarction and its triaging. Interpretation of lipid and non- lipid cardiovascular markers is given. The chapter ends with presenting the Instrumentation involved in turbidimetry along with Trouble Shooting issues.