A design for an in situ soil solution sampler (suction lysimeter), consisting of a stainless steel tube with a 0.1 MPa(-1.0 bar), high flow, porous ceramic cup, is presented for use in monitoring pesticide or other dissolved chemical leaching in the vadose (unsaturated) zone. The sampler is of one piece construction with the porous ceramic cup attached by epoxy adhesive. The design permits collection of a total volume of up to 0.5 of soil solution per sample. Laboratory studies indicated that pesticide sorption on the sampler was insignificant and no analytical interference problems were observed. The samplers were designed to monitor leaching of pesticides and inorganic tracers in an on-going field study in southwest Georgia.