The assimilation of polychlorinated biphenyls (PCBs) in round gobies (Neogobius melanostomus) after intraperitoneal (IP) injection was compared to PCBs bioaccumulated by the same fish through natural exposure ("native" PCBs). Lipid equivalent corrected dorsal muscle: whole body concentration ratios for native PCB 153 averaged 1.16 ± 0.77 and ranged from 1.19 to 1.24 for three IP dosed non-native PCBs within 6 h after dosing. Variation in tissue distribution of IP-dosed congeners was reduced after benchmarking to PCB 153, reinforcing that assimilation of the IP dose occurred into muscle rapidly after injection. Despite the use of small oil volumes during injection (<10 μL per fish), coefficients of variation of IP-dosed PCBs were equivalent to those observed for native PCBs. The results suggest that IP dosing provides a precise method to achieve target concentrations of hydrophobic chemicals in small fish and does not require several days to achieve assimilation into highly perfused tissues.