Our laboratory has been experimenting with using commercially available ground water immunoassays to analyze urine samples from workers exposed to the herbicides alachlor (ALA), metolachlor(MET), atrazine (ATZ), cyanazine, and 2,4-D. Several issues related to using these kits for urinary biomonitoring have been addressed in this study, including matrix effects and cross reactivities of the kit antibodies with metabolites of the herbicides and with other chemically-related herbicides. In general, dilution of the urine has proven satisfactory in removing matrix effects for all the kits except 2,4-D. The ALA and ATZ kits showed cross-reactivities with their respective mercapturate derivatives, whereas the MET kit showed cross-reactivities with other acetanilides, but no reactivity with MET-mercapturate. These issues, along with considerations involved in determining LOD and linearity range, will be discussed. In addition, results from experiments involving direct-reading field immunoassay kits will be discussed.