Recombinant adeno-associated virus vectors are one of the most promising gene delivery tools for applications within gene- and cell therapy. The high level of wild-type adeno-associated virus infections in humans is a limitation due to the pre-existing immunity against the vector or its transgene product. An important tool to develop effective and safe therapies is the ability to measure the pre-existing immune responses against the virus capsids in humans. This master thesis at Gyros Protein Technologies aimed to investigate if the Gyrolab immunoassay system can be used to screen for pre-existing anti-capsid immunity in human sera by optimizing and evaluate three different assay formats: an indirect assay, a generic anti-AAV adsorption assay and a bridging assay. The evaluation focused on immunity against adeno-associated virus serotype 2. All immunoassay formats performed well and depending on application, the different formats offers different advantages. The generic anti-AAV adsorption assay offers the ability to easily screen for several viral serotypes without having to label the capsid, and the bridging assay provides high sensitivity. When screening 31 individual human sera, 58% were positive using the indirect assay and the generic anti-AAV adsorption assay and 65% using the bridging assay format. Provided, is automated and high throughout immunoassays where 16 individuals can be screened in one-two hours. It is shown that all three immunoassay formats can be used to screen for anti-adeno-associated virus antibodies, even though further optimization, cut off development and a larger data set is needed to obtain a fully sophisticated screening tool.