The aim of this study was to evaluate the phenolic and flavonoids contents and the antioxidant and antitumoral activity of leaf and calyx methanolic extracts from Hibiscus sabdariffa (roselle) cultivated with poultry litter and organosuper® under three modes of application. The total phenolic content in the each extract was determined using the Folin-Ciocalteu reagent and for aluminium chloride flavonoids. The antioxidant parameters were analyzed using a 2, 2-diphenyl-1-picrylhydrazyl (DPPH.) free radical scavenging assay. An antitumor colorimetric assay using sulforhodamine B. The highest contents of phenolic and flavonoids were observed in leaf extracts (389.98 and 104.52 mg g-1, respectively) and calyx extracts (474.09 and 148.35 mg g-1, respectively) from plants cultivated with organosuper®, although these values did not differ significantly from those observed for the other treatments. The average IC50 of leaves (43.48 μg mL-1) and calyces (37.15 μg mL-1) demonstrated that both have substances that may contribute to free radical scavenging action. The methanol extract from calyces showed significant selective activity against a leukemia line (K-562), with IC50 values of 0.12 mg mL-1 (organosuper®) and 1.16 mg mL-1 (poultry litter), with concentration-dependent, cytotoxic and cytocidal effects.