A survey was carried out in three provinces of Mozambique with different agroecological conditions to document traditional knowledge related to cultivation and use of indigenous watermelons, and to describe the diversity of landraces within the country. Semi-structured interviews were used to collect information at the household level or in farmers' watermelon fields. Watermelons were intercropped with the main cereals, mainly sorghum in the driest areas and maize in the more humid areas. Three main types were found: A dessert type with sweet, white to red, spongy flesh, a seed type with white either firm or spongy flesh, and a cooking type with yellow, firm flesh. Watermelon was an important food item consumed before harvest of cereals in the surveyed areas. Sweet dessert types were marketed in both local and urban areas. Only local landraces were cultivated, mostly from farmer-saved seed. Primary in-situ description of fruit and seed characters revealed a considerable variation. Significant differences were found among provinces for rind thickness, flesh colour, and seed size. This study highlighted that traditional knowledge related to the cultivation and use of watermelons, and that indigenous landraces persist in Mozambique. Key words: Citrullus lanatus, cropping systems, ethnobotany, germplasm, landrace, traditional plant use, Mozambique, watermelon.