The macroscale and mesoscale structure of the interplanetary magnetic field during the primary mission of Helios 1 is discussed. The radial field component behaves essentially in agreement with Parker's theory. The transverse component shows a larger variability than the radial component; it radial variation is in good agreement with Parker's theory for high speeds, but some deviation is found for low speeds. The radial variation of the field variance is also studied. Its dependence upon the heliocentric distance r is expressed by the law r3, which is necessary but not sufficient for Alfv¿n waves. The available data do not allow a unique interpretation of the r-3 dependence. No big differences are observed between low (?500km/s) and high (?600 km/s) solar wind velocity regimes.