Galaxy Evolution: The ISOCAM View

New observations of nearby and distant galaxies in the mid infrared with ISOCAM have been used to study the star formation rate in these galaxies. The mid infrared flux density is a good indicator, similar to Hα, in the disk of spiral galaxies. In more active starburst, the mid infrared traces the youngest star formation complexes, still embedded in dust. A strong evolution of L15μm/LBluminosity ratio is observed in large distant galaxies. This is attributed to strong starburst events triggered by a larger number of galaxy-galaxy interaction at redshift > 0.5.