  We present the results of infrared observations of Abell 1689 which was
observed with ISOCAM, at 6.7\mic and 15\mic, and ISOPHOT at 200\mic. The
cluster galaxies detected above a sensitivity limit of 0.15 mJy in the 6.7\mic
band, whose emission is mostly dominated by their stellar component, show
optical colors similar to the overall cluster population and are gathered in
the center of the cluster, following the distribution of the cluster
early-types. In the 15\mic band, above a sensitivity limit of 0.3 mJy, the
galaxies spectroscopically confirmed to be cluster members are blue outliers of
the cluster color-magnitude relation and become brighter going from the center
to the outer parts of the cluster.
  We compare the 6.7\mic and 15\mic fluxes and the cumulative distributions of
the B-[6.75] and B-[15] colors of the A1689 galaxies, above our 90%
completeness limits of 0.2 and 0.4 mJy for 6.7\mic and 15\mic respectively, to
the galaxies of two nearby clusters, Virgo and Coma, and to the field galaxies
at the same redshift of the cluster. Although the B-[6.7] color distributions
of the three clusters are compatible, we find a systematic excess of B-[15]
color distribution for the galaxies located in Abell 1689 with respect to Coma
or Virgo galaxies. This result proves the existence of a mid-infrared
equivalent of the Butcher-Oemler effect measured in the optical. The comparison
of 15\mic flux and B-[15] color distributions of A1689 and field galaxies does
not show strong differences between the population of starburst galaxies in the
cluster and in the field.
