Grafting is an alternative approach to reduce crop damage resulting from soil-borne pathogens. This approach also increases plant abiotic stress tolerance, which in turn increases crop yield and quality. Therefore, the objective of this study was to determine the effect of grafting on watermelon quality parameters with the use of different rootstock combinations. Different morphological characteristics (yellow-red fleshed, with seed-seedless, striped rind and dark green rind) were grafted on rootstocks of Argentario (Lagenaria spp.) and Maximus (Cucurbita maxima x C. moschata). While the highest fructose, sucrose and soluble solids content were measured in Argentario/TP84, TP84 had the highest glucose content. Total carotenoids content in watermelons ranged from 15.36 +/- 2.78 to 104.51 +/- 12.04 mg kg(-1). Argentario/TP84 showed the highest level of lycopene (93.95 mg kg(-1)) among cultivars and combinations. beta-carotene content varied from 1.44 +/- 0.01 to 3.76 +/- 0.01 mg kg(-1). The highest ascorbic acid content was in Argentario/TP84 (17.26 mg kg(-1)), followed by Argentario/5299 (17.26 mg kg(-1)). Grafting significantly increased soluble solids, sugars (fructose, glucose and sucrose), total carotenoids and ascorbic acid contents. Maximus/Ant09 had the highest total carotenoids and lycopene content but lowest fructose, sucrose and soluble solids content on C. maxima x C. moschata combinations, whereas Argentario/TP84 has the highest fructose, sucrose, soluble solids, total carotenoids, beta-carotene, lycopene and ascorbic acid contents among cultivars and combinations. This study showed that use of bottle gourd (Lagenaria spp.) rootstock could enhance soluble solids, fructose, sucrose, lycopene and ascorbic acid contents in watermelon.