The concentrations of the cosmic-ray-produced He, Ne and Ar nuclides in 16 iron meteorites were determined by mass spectrometric isotope dilution techniques. Four of these meteorites show a 3He deficit which presumably is caused by tritium loss during irradiation. For the other meteorites the relative abundances of the various spallogenic rare gas nuclides can completely be described by a “primary correlation system” consisting of 6 equations: (1) 3He/ 4He = f 1( 4He/ 21Ne), (2) 3He/ 38Ar = f 2( 4He/ 21Ne), (3) 20Ne/ 21Ne = 0.94, (4) 22Ne/ 21Ne = 1.07, (5) 36Ar/ 38Ar = f 5( 4He/ 21Ne), (6) 40Ar/ 38Ar= f 6( T). The functions f 1 to f 5 follow from the experimental results. Function f 6 is essentially determined by the decay of spallogenic 40K into 40Ar during the cosmic ray exposure age T. Accordingly the relative abundances of the rare gas nuclides in a sample are completely, unambiguously and with a relatively good precision determined by the two quantities which are the independent variables of the primary system, namely by the “effective irradiation hardness” 21Ne/ 4He and by the exposure age T. The present experiments do not, however, provide the information on the purely spallogenic 40Ar/ 38Ar ratio and hence on the exposure age T. A large number of “secondary” correlations can be derived from the primary system by simple calculations. An example is correlation (9): 4He/ 38Ar = f 9( 3He/ 21Ne), which follows from (1) and (2). For 3He/ 21Ne < 90 it agrees with Signer and Nier's experimental results, but for 3He/ 21Ne > 90 it deviates from the predictions of their model. The model must obviously be modified for samples from large depths in large meteoroids. The conception of primary and secondary correlations is helpful for a general discussion of the question what information can, in principle, be deduced from a single rare gas analysis on the particular irradiation circumstances of the respective sample. It is shown that the usual techniques of rare gas analysis which do not determine the purely spallogenic 40Ar, can only provide an information on the effective irradiation hardness (i.e. on the independent variable of equations (1) to (5) or of any otherwise choosen “primary” equations which do not contain 40Ar). But these techniques do not allow one to ascertain the exposure age and the size of the meteoroid and the original location (depth) of the sample within the meteoroid. In order to ascertain the size and the depth, the exposure age T must supplementary be determined by an independent method. But it follows from correlation (9), that for samples from large depths the possibilities for the interpretation of rare gas data are still more restricted.