The detection of antibiotics in water and sediment systems is of concern due to the potential adverse effects which could be associated with their environmental fate. The central aim of this study was to evaluate the fate of erythromycin in microcosms consisting of pond water and submerged pond sediment. The first study examined the dissipation of erythromycin from spiked water and total recovery of [14C]-erythromycin from water and sediment within microcosms ranged between 90.1% and 48% throughout the 63-day study. Erythromycin was reduced in surface water of sediment-containing systems by day 7, which corresponded to an increase of eryrthromycin detected in sediment. In the second study the availability of aged erythromycin was evaluated by incubating sediment with and without a manure amendment with [14C]-erythromycin for 0, 1, 3, or 8 weeks; followed by assessing movement and availability of erythromycin in sediment microcosms after 1, 3, 7, and 14 days. Results indicated differences in residues from aged sediment, with and without manure additions, in extractable residues at day 7 and 14. The addition of manure resulted in greater extractable erythromycin from aged sediments than from sediments without manure. There was a greater release of erythromycin to the water overlying the manure-treated sediments with fresh and 1 week aged sediment than the unamended sediment after 1 and 2 weeks. The results from this experiment demonstrate the ability of manure to influence the fate of erythromycin in environmental matrices.