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The presser broadening of the hyperfine lines of the $\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}p1/2-2p3/2$ atornic iodine transition is of importance in the chemically pumped iodine laser. The hyperfine lines are observed in emission with a high resolution Fourier Transform spectrometer after dissciation of $I2$ by the $4965nmAr4$ lines. Pressure broadening of 1.95 MHz/torr, 39 MHz/torr and 193 MHz/torr were observed by colilisiton with Argon Oxygen and Iodine respectively. We have tried to caluculate theoretically these enlargements by a semi-classical method. Relaxation cross-sections are calculated between hyperfine levels of the I atom, in the first order Born approximation. The intraction potential is a second order long-range potential, described as a multipolar expansion between $O2$. Ar or $I2$ and I atom and calculated from molecular or atomic polarlsabilities.