Accurate and sensitive methods for measurement and detection of cytokines are important for the understanding of cytokine biology and biochemistry and the assessment of cytokine involvement in pathology and physiological processes. Various types of assays are available for estimation of cytokine levels in biological fluids. Often, immunoassays are used for this purpose but in many cases inappropriate assay choice, design and standardisation have led to confusing or erroneous data and conclusions. Only if well characterized, validated and standardized methods are used and results carefully analysed can useful unambiguous information be obtained. This article contributes significantly towards the standardisation, calibration and validation aspects of immunoassays for cytokines.