This study examines the conditional sentence structures in Igbo and Tongan languages and aims to reveal the similarities and differences between these languages regarding the semantic structure and syntactic characteristics of the conditional clauses. Therefore, the contrastive analysis procedure is applied which consists of three steps as (1) description; (2) juxtaposition; (3) comparison (Krzeszowski, 1990). In pursuit of the description of the conditional sentence structures in Igbo and Tongan languages, they are juxtaposed and compared. This contrastive analysis procedure revealed that Igbo and Tongan languages have both the first, second, and third conditions. In addition, Tongan has also zero conditions. Moreover, they may use differe...