1. The patterns of HSP70 expression induced in Caenorhabditis elegans by mild (31°C) or severe (34°C) heat shock, and by cadmium ions at 31°C, have been compared with those expressed constitutively in 20°C controls by 1- and 2-dimensional immunoblotting.2. The 2D spot patterns become more complex with increasing severity of stress (34°C > 31°C + Cd > 31°C > 20°C).3. A stress-inducible transgene construct is minimally active at 31°C, but is abundantly expressed in the presence of cadmium or at 34°C.4. Differing degrees or types of stress may differentially induce available hsp 70 promoters.