It is possible to assess the complexity of text to determine the level of lexical density (LD) and grammatical intricacy (GI). This study seeks to discover how much complexity can be identified in the introduction part of bachelor’s theses. Qualitative analysis was utilized as the research design in this study. The words, phrases, and clauses were used as the data taken from the data sources of 20 introductions of the undergraduate theses in the English department of Universitas Sumatera Utara. The findings showed that the lexical density score is 53.54% and grammatical intricacy score is 2.542. The LD score obtained means that the characteristics of the written language used is suitable because the written text has a lexical density of more than 40%. Meanwhile, the grammatical intricacy shows that many clauses were used by students in writing the introduction of their thesis. This means that the students’ text were complex and more intricate.