N-ethyl-N-nitrosourea and 4-nitroquinoline-1-oxide were evaluated in the allohexapolyploid wheat seedling assay for their ability to induce aneuploidy and/or small chromosome deletions. The wheat strain used (Neatby's virescent) is homozygous for a pair of recessive alleles (v1) present on chromosome 3B and produces virescent seedlings when grown at temperatures below 26 C. When the germinating embryos are treated with a test chemical, loss of chromosome 3B or its segment bearing the v1 allele produces a green sector in the leaf whereas a gain of this chromosome induces a white sector. Both the test chemicals yielded positive results in this assay. The assay is very simple and can be employed for evaluating the genetic potential of chemicals in a laboratory as well as for in situ hazards assessment under natural environmental conditions.