Technical Abstract: A reliable quantitative bioassay is required in order to study host pathogen interactions. For chickpea Ascochyta blight, a number of techniques were reported. However, those available techniques could not produce reproducible results in our growth chamber or greenhouse conditions. We made an important improvement in conducting bioassay of Ascochyta blight and the improvement made the bioassay reproducible. The improvement consists of covering inoculated plants with tranparent plastic cups to generate a uniform high level of relative humidity for infection to occur. The improved technique significantly reduces variation among replications of treatments. With this technique we were able in repeated trials to show geographic variations among isolates collected from various locations in California, Idaho and Washington. The development of this technique will allow us to address research questions concerning interactions between Asochyta rabiei and chickpea genotypes. This improved technique can also be implemented in resistance breeding to screen breeding materials.