Abstract: Based on the Indonesian Government’s Regulation No. 82/2001 on Water Quality Management and Water Pollution Control, it was previously studied that heavy metal pollution in river stream in Indonesia, especially heavy metal Zn (zinc), has exceeded the maximum threshold for water quality Class I, II and III. One of the applicable methods that can be expected capable to deal with such heavy metal pollution problems is phytoremediation, i.e., the use of plants or plant parts as a natural biological treatment system. In this research, zinc uptake and accumulation by hairy root cultures of Solanum nigrum (black nightshade) were studied. Two strains of Solanum nigrum hairy roots were used, i.e., strain A4 and strain K1 (control). Up to 18.64 mg Zn L-1 medium were supplemented to the culture medium. The results showed that both strains were still capable growing well in the culture medium supplemented with 13.98 mg Zn L-1 medium. Strain A4 was capable in accumulating Zn from the culture medium better than the strain K1; however, both strains of hairy roots have similar patterns in terms of growth and metal absorption. Up to 98% Zn was accumulated by the strain A4 within 15 day of the culture period, while the strain K1 was capable in accumulating 90% Zn within 18 day of the culture period. Both strains reached maximum Zn accumulation at day 9 with strain A4 accumulated Zn slightly higher than the strain K1, i.e., 1.08 and 0.84% for strain A4 and strain K1, respectively.