The expression of hsp 70 after heat shock or exposure to heavy metals/molluscicides was investigated by fluorography or immunoblot in three diplopods (Glomeris marginata, Cylindroiulus punctatus, Tachypodoiulus niger), two slugs (Deroceras reticulatum, Arion ater), and one isopod (Oniscus asellus). In O. asellus, hsp 70 expression occurred after heat shock and also after lead treatment, whereby a solution of 100 mg/kg Pb2+ was sufficient. Animals of the same species taken from a heavy metal polluted site in the vicinity of a lead/zinc smelter also showed the presence of hsp 70. The comparison of laboratory and field experiments demonstrated the suitability of O. asellus for monitoring tests. In contrast, the blot pattern after contamination with 1,000 mg/kg Pb2+ (in the mentioned diplopods) or different concentrations of the molluscicide Cloethocarb (BASF, FRG) (slugs) showed no differences compared to the respective control group.