In the Netherlands, national screening programs for breast and cervical cancer are operating, whilst that for colorectal cancer is in preparation. In the meantime, experimental studies have been conducted into the effectiveness of prostate and lung cancer screening. Death from these five types of cancer is reduced by these screening investigations. However, these screening programmes also have disadvantages, such as unnecessary referral for definitive diagnosis in the hospital. The average hospital would receive on a yearly basis via screening 156 referrals of women with breast cancer, 79 for cervical cancer and nearly 1100 persons for colorectal cancer. n average general practice encounters annually 3 positive screening results for breast cancer, almost 1 referral for cervical carcinoma or an early stage thereof, and every two years a patient with CIN III. For colorectal cancer around 22 referrals can be expected yearly, of which 8 will have adenoma or cancer.