One year ago a new specific test for the detection of cancer was presented. The authors described a new method to measure the line width of lipoproteins in plasma by NMR-spectroscopy. Their results showed a significant decrease of the line width in plasma of patients with cancer compared to normals. The present study gives the results of a cooperative investigation in our institutes to prove the reliability of the so-called Fossel test. We investigated 100 samples, including 27 healthy persons, 13 pregnant women, 13 patients with non malignant and 47 patients with malignant disease without any tumor treatment. Blood samples were drawn after an overnight fasting and EDTA plasma was stored at -18 degrees C NMR spectroscopy was performed by an AM Spectrometer by using deuteriumoxide and water suppression by a decoupling power of 9 L. The mean line width was found 41.07 +/- 6.08 Hz for healthy and 34.40 +/- 10.80 for patients with non malignant diseases. Patients with cancer and other hematological diseases showed a mean of 35.40 +/- 8.0 Hz. Only in pregnancy a significant decrease of the line width (mean 32.60 +/- 5.7 Hz) was observed. Only small differences between normals, patients with cancer and patients with non malignant disease could be found. The wide range of the line width did not allow any discrimination between malignant and non malignant disease.