Andaliman (Zanthoxylum acanthopodium DC.) is a spice plant typical of North Sumatra. Biological information on andaliman flowers is still limited. Therefore, the purpose of this observation is to study morphology of andaliman flowers and inflorescence arrangements that can be useful in understanding andaliman flower biology. The research was conducted on plants in one of the centres of andaliman production in Dairi District. Flower of andaliman is axilliary inflorescence, determinate flowers, dichasium, generally glomerate, the number of flowers in one peduncle varies greatly. The time blooming of the flowers in each rachis is quite varied. Flower andaliman small and hermaphrodite with its parts, sepals 5-7 free, pale yellow colour, 5-6 stamens, anther is reddish, pollen sticky, and 3-4 pistils, and sometimes 5 pistils, apocarps. Information obtained from this study can be used in subsequent studies related to pollination, fertilization, fruit set, and seed set. The variation of flower blossom in one peduncle is one of the factors contributing to the maturity of the fruit as a source of seed should be studied.