A brief review is given of mechanical property measurements on oxide films. This review is followed by a detailed discussion of the mechanical and fracture properties of anodic aluminum oxide films as observed in the author's laboratory. Extensive measurement of Young's modulus,
E
c
,and fracture strain,
ε
f
, for separated films 3000Aå thick is reported as a function of environmental water vapor pressure. The fracture of these unsupported films is shown to occur by a brittle mechanism. Mechanical properties of adhering aluminum oxide films are given as a function of their thickness. These oxides were observed to fracture either at slip steps, or at right angles to the tensile axis in a regularly spaced fashion. A theory of adhering oxide fracture is discussed which accounts well for the observations. An equation which describes the spacing
d
of regular oxide fracture cracks as a function of substrate strain ε is given in the form
ln
(
ε
/
ε
0
)
=
k
√
t
(
1
/
d
−
l
/
d
0
)
, where (
ε
o
,
d
o
) are the initial conditions for regular fracture,
t
is the oxide thickness, and
k
is a constant.