We study orthogonality preserving and approximately orthogonality preserving mappings in the setting of inner product
C*-modules. In particular, if
V and
W are inner product
C*-modules over the
C*-algebra
, any scalar multiple of an
-linear isometry is an
-linear orthogonality preserving mapping. The converse does not hold in general, but it holds if
contains
(the
C*-algebra of all compact operators on a Hilbert space
). Furthermore, we give the estimate of
Tx,Ty−T2x,y for an
-linear approximately orthogonality preserving mapping
T:V→W when
V and
W are inner product
C*-modules over a
C*-algebra containing
. In the case
and
V,
W are Hilbert, we also prove that an
-linear approximately orthogonality preserving mapping can be approximated by an
72392e23e193"">-linear orthogonality preserving mapping.