This is a preliminary report of an outreach mammographic-screening programme on Crete. The screening is part of a study to test if occupational exposure to pesticides in greenhouses (mainly organophosphates and organocarbamates), may increase the risk of malignant or premalignant findings in mammographic examination. A total of 1062 women (aged 40--75 years) were recruited between 1988 and 1993 and followed-up until 1998: 522 worked for at least 10 years in greenhouses for more than 4 h daily (exposed), and 540 never worked in agriculture (non-exposed). Statistics include detection rates and relative risks of mammographic findings. 'Exposed' women had a significantly (P<0.05) higher risk than 'non-exposed' for fibroadenoma, ductal hyperplasia, sclerotic adenosis, fibrohyperplastic disease, cystic disease and inflammatory mastitis. There were no significant differences in the detection rates of fibrocystic changes, lipoma and malignant changes or malignant tumours. Compared with older women (aged 50--75 years), younger women (aged 40--49 years), particularly in the 'exposed' group, had a higher detection rate of malignant tumours. These preliminary results indicate that 'exposed' women may have higher risks of incidence for a number of lesions, which are risk markers for subsequent invasive breast cancers. They confirm also that early screening for breast cancer is effective and provides an opportunity for a reduction in breast cancer mortality.