[en] This report compiles all available results of the EERF's participation in interlaboratory comparison programs. In general the results are satisfactory, although there are some areas of concern. A summary of all analyses for the predominant radionuclides included in this report is presented in tabular form. Also included are the results reported for unspiked samples. Results for the unspiked samples reported as not detectable (ND), zero, or as a value less than the assigned minimum detectable level (MDL) were considered to agree within +- 10%; a value reported as greater than the MDL was considered unsatisfactory. For the 753 specific radionuclide analyses, 75% and 92% were measured within +- 10% and +- 20%, respectively, of the Reference Center values. These data are presented graphically where the cumulative probability is plotted with the observed percent error. The probability that the result of an analysis will be within a selected error of the true concentration can be easily ascertained from the graph. The most important function of intercomparison programs is to identify problem areas. If a problem exists, immediate remedial action should be inititated. Errors can occur for numerous reasons; improperly following a tested procedure, arithmetical errors in the calculations, permitting contamination to enter the sample during analysis, undetected fluctuations in counting efficiencies, or backgrounds, and using incorrect weights, or absorption factors