A crop exposure matrix (CEM) was developed in the context of two Italian case-control studies. The CEM relates agricultural practices to pesticide exposures taking into account change over time and the use of chemicals by geographical area for farming. The matrix is specific to 14 areas and to 10 major crops. The exposure axis is made up of 440 chemicals used in the last 40 years in the areas of interest. In the matrix the association between crop growing and pesticides is expressed in terms of presence or absence of exposure. Accuracy of the matrix was initially evaluated using 26 occupational histories collected within the two case-control studies. Sensitivity and specificity of CEM for some compounds were estimated versus assessment of exposure by experts. Sensitivity ranges from 83.3% to 100%, specificity from 66.2% to 95.8% depending on the chemicals.