The spallogenic isotopes of helium, neon, and argon have been measured in 36 iron meteorites using a statically operated double focusing mass spectrometer. The following relations were found between the concentration ratios of the cosmic ray produced isotopes 3He, 4He, 21Ne, and 38Ar: 3He/4He = (36.0 ± 0.9) 21Ne/4He+ (0.148 ± 0.015), 38Ar/21Ne= (9.4±0.8) x 10-34He/21Ne+ (2.06±0.04). From the 38 Ar/21Ne ratio a parameter n was calculated for each sample which according to GEISS, OESCHGER und SCHWARZ is a number measuring the effective irradiation hardness. Relations between n, 3He/4He, 3He/21Ne, and 4He/21Ne have been studied. A slight variation of the 36Ar/38Ar has been found which is correlated to the effective irradiation hardness. The spallation yield of 36Ar relative to the total isobaric yield does not depend on the effective irradiation hardness.