Acrylamide (CH2CHCONH2), the vinyl monomer of the industrially useful polymer polyacrylamide, is a recognised neurotoxin. Investigation in our laboratory indicated that, in addition to its neurotoxic effect, acrylamide depressed human polymorphonuclear leucocyte (PMN) chemotaxis in vitro. As genetic or chemical inhibition of PMN phagocytic function frequently pre-disposes patients to repeated bacterila infections, the in vitro effects of acrylamide on several other human PMN functions were studied. Acrylamide in concentrations up to 37.5 mg/ml had no effect on trypan blue uptake. However, bacterial ingestion, killing, and induced chemiluminescence were depressed by pre-treatment with acrylamide (10 mg/ml). It seems unlikely that acrylamide exposure alters host resistance to bacterial infections, because (a) large doses of acrylamide are necessary to interfere with phagocytic functions, (b) acrylamide reacts readily with proteins on many tissue cells and may be made inaccessible or non-toxic to PMN'S and (C) PMNs have a rapid turnover rate in the body and non-functional cells would be rapidly replaced by functional cells.