Mineral scale is a major flow assurance problem in industrial water systems. The antiscale properties of sunflower (Helianthus annuus) seed extract for CaSO4 and BaSO4 scales were investigated using NACE and conductivity tests, respectively. Comparative studies between the extract and 1-hydroxyethane-1,1-diphosphonic acid (HEDP), as commercial antiscalants, were done. The results revealed that the inhibition of CaSO4 scales using sunflower seed extract reached 100%, while HEDP achieved a maximum inhibition of 88%. Moreover, the maximum inhibition of BaSO4 scale in the presence of the extract was 84% compared with 86% in the presence of HEDP. Also microscopic examination showed that both inhibitors modified CaSO4 and BaSO4 crystals.