Haemoccult was compared once more with hemoFEC after improvements of the latter material in 1979. 3200 patients were tested parallel with both materials. Haemoccult was positive in 149 patients = 4.6%, hemoFEC was positive in 129 patients = 4.0%. With Haemoccult 22 cancers and 26 large polyps were traced, with hemoFEC 20 cancers and 25 adenomas. 2 cancers and 19 large polyps were negative with both tests. Since 1972 a total of 25.700 patients have been tested with Haemoccult as part of the routine check-program, 873 = 3.4% had a positive test. Of the 600 examined, 124 had colorectal cancer and 196 had a large polyp. By reviewing the charts of all cancers and polyps diagnosed, 19 out of 143 cancers = 13% and 136 out of 332 polyps = 41% had a false-negative Haemoccult test on one-time, initial testing.