Syzygium Gaertn. (Myrtaceae) is the most diverse tree genus, having ca. 1200 species distributed in tropical and subtropical regions of the Old World. Its diversity center is in Malesia, but the genus is generally thought to have an austral origin. As one of the most common forest elements, Syzygium inhabits a variety of vegetation types such as lowland to montane rainforests, swamps, savannahs, and limestone forests. Its fleshy fruits (cultivated as rose apples) are an important food source for forest animals. Syzygium leaves usually display typical myrtaceous architecture, including pinnate brochidodromous venation with the secondary veins connecting to form intramarginal veins. However, this venation pattern is also observed in most other families in Myrtales and in many distantly related families, e.g., Apocynaceae. Thus, leaf architecture alone is unreliable to infer myrtaceous affinity and generic assignment of fossil leaves. Nearly all previous ‘Syzygium’ leaf fossils require reexamination, and perhaps the only unequivocal leaf record is from the early Miocene of southern Australia. Recent studies have revealed characteristic micromorphology on modern Myrtaceae leaves and their infrafamilial patterns, allowing for the identification of myrtaceous fossil leaves using cuticular analysis. Here, we report fossil leaves of Syzygium with in-situ cuticles from a Pliocene site in the Kon Tum Formation in Central Highlands Region of Vietnam. Overall, the Kon Tum flora is characterized by relatively small-sized and predominantly entire-margined leaves, with more than 40 morphotypes recognized so far, also including Ficus, Dipterocarpaceae, Fabaceae, Lauraceae, and others that suggest a tropical monsoonal forest similar to modern regional floras. The myrtaceous leaves are mostly preserved as dark or brown compressions that are easily detached from the matrix. They are elliptic-narrowly elliptic to obovate in shape, having an acute and acuminate apex and a decurrent to cuneate base. The venation is brochidodromous, with intersecondary veins common and more than five pairs of secondary veins forming distinctive intramarginal veins, but the tertiary and higher venation is not clear. The leaves are hypostomatic, with cavity-like structures on the abaxial side interpreted as lid-cells, a characteristic feature of Myrtaceae. Both leaf surfaces completely lack trichomes, suggesting the tribe Syzygieae. The stomatal complex is paracytic or anisocytic, scattered evenly and densely, which is consistent with Subg. Syzygium. The epidermal cell flange is straight. Syzygium leaves are the most abundant element in the Kon Tum flora, accounting for over 30% of the specimens (ca. 186 out of 572), implying either proximal deposition or high abundance in the flora. A possible Syzygium pollen grain was also recovered from the same outcrop, exhibiting the characteristic triangular polar view and apocolpial field of the genus. This study provides the first Syzygium leaves with in-situ cuticles in the Northern Hemisphere. Earlier records are the early Miocene leaves from Australia and a Miocene wood attributed to the genus from South China, indicating that the dispersal from Australia to Asia occurred no later than the Miocene. The new leaf fossils show that forests with abundant Syzygium have already been established in central Vietnam since at least the Pliocene.