The U.S. Environmental Protection Agency has standardized methods for performing acute marine amphipod sediment toxicity tests. A test design reducing sediment volume from 200 to 50 ml and overlying water from 600 to 150 ml was recently proposed. An interlaboratory comparison was conducted to evaluate the precision of this reduced sediment volume toxicity test method using the marine amphipod Ampelisca abdita. A negative control and three sediment samples of varying degrees of toxicity ranging from low to high were tested by six laboratories. Complete agreement was reached in rank of relative toxicity for all samples tested by five out of six laboratories. Test acceptability for control survival was achieved by all laboratories, and 69% agreement in classification of the sediments as toxic or nontoxic was documented. Coefficients of variation in all test samples were similar to those reported in other interlaboratory studies using marine amphipods. Results of this study indicate that the reduced sediment volume test using A. abdita is a reliable and precise measure of acute toxicity in marine sediment samples.