As part of a two-phased study, sediment and biota were collected from Pennekamp Coral Reef State Park and Key Largo National Marine Sanctuary and analysed for organochlorine pesticide residues. Phase 1 consisted of an inter-laboratory comparison using replicates of unspiked field samples. The five participating contract-laboratories differed in methodology, detection limits and their ability to detect pesticides. The highest concentration of pesticide reported in Phase 1 samples was 4.4 ng g−1 wet wt aldrin, found in a fillet of Haemulon plumieri. Based on the inter-laboratory comparison, one laboratory was selected to analyse additional samples collected in Phase 2. Pesticides were detected in 43 of the 52 Phase 2 samples. The highest concentration reported in Phase 2 samples was 2.3 ng g−1 α-BHC in Panulirus argus tail muscle. These results suggest that while most samples contained one or more residues, pesticide concentrations were low and trends in residue profiles were minor.