Linear, branched, and grafted polyamine flocculants were synthesized and applied for dye wastewater treatment. The effect of polyamines on color removal was investigated by comparing two treatments: (i) alum alone and (ii) alum/polyamine in combination. Compared to alum alone treatment, the use of polyamine flocculants in combination with alum was highly efficient in color and turbidity removal. Addition of a small amount of polyamine (40 mg/L) reduced alum dosage by 50% while improving color removal efficiency by 20%. Branched polyamines were more efficient than grafted polyamines presumably because branched polyamine has higher charge density than grafted polyamine. Our results indicate that the use of alum/polyamine system is beneficial in dye wastewater treatment. The effects of polyamine flocculants on total organic carbon removal and zeta potential were also discussed.