This study aims to investigate the inter-rater agreement of the Main Concept Analysis (MCA), a proposition-based system for analyzing the presence, accuracy, completeness, and efficiency of content in spoken narratives of speakers with aphasia. Twenty-one MCA assessments were administered to thirteen participants recruited from an intensive aphasia treatment program. Six MCA indices were applied to the language samples, which were cross-checked to determine discrepancies of results across raters. The present results were consistent with similar studies in the literature, thus indicating that the Main Concept Analysis is a reliable assessment battery. Given the simple, quick, but objective procedures for language quantification, it is argued that the Main Concept Analysis can easily be adopted to the Korean-speaking population for clinical analysis of discourse.