Harnessing food wastes utilization in diets and drugs could improve food supply, health and the environment while antinutrients composition in a food provides an idea of the pharmacologic, dietary and toxic potentials of the food. Thus, this study assessed the antinutrient properties of the rind and seed of watermelon (Citrullus lanantus) which are usually discarded as food wastes in Nigeria, using standard protocols. The antinutrients (mg/100 g) in the rind and seed, respectively viz: saponin (3.0±0.03, 2.31±0.01), alkaloid (1.39±0.00, 0.36±1.03), tannins (1.33±0.01, 0.61±0.01), phenol (0.53±0.00, 0.12±0.01) and flavonoid (2.87±0.00, 2.03±0.02) were higher in the rind than in the seed. The content (mg/100 g) in the seed for cyanide (0.79±0.01), phytate (0.63±1.00) and oxalate (0.09±0.00) was higher than that in the rind for cyanide (0.00±0.00), phytate (0.46±0.00) and oxalate (0.08±0.01). The recorded difference in the antinutreints content in the rind and seed samples was not significant (p>0.05), hence negligible. The preponderance of these antinutrients in a comparatively lower amount in the samples suggests that the watermelon rind and seed may offer pharmacologic and dietary benefits at a possibly lower toxic risk. Thus, the study supports the use of watermelon rind and seed as food and/or as drug in ethnomedication. Further studies to harness and enhance the utilization of watermelon rind and seed in diets and drugs are required to reduce their attendant waste burden in the environment.