Although it is not quietly supported nowadays, some linguistics and orientalists believed/proposed that due to the large resemblance between the two and somehow mutual ineligibility, Kurdish is a dialect of Persian. The objective of this paper was to answer this hypothesis from a lexical point of view. Lexical Similarity measures the similarity and/or difference between a set of words from any given two languages. Despite the abundance of lexical similarity coefficients between various world languages in the literature, there are no available data on Kurdish and Persian, even though many Kurdish natives learn Persian as a second language. Our results showed (51.5 %) lexical similarity between Persian and Kurdish by using the Leipzig-Jakarta list. This result shows close proximity and common genetic roots between these two languages. However, it is not high enough to claim a dialect relation between the two; like, for example, 85% similarity index between Catalan and Spanish. Hence, this outcome, in a lexical point of view, is against the hypothesis of ‘Kurdish is a dialect of Persian’.