  We present the first INTEGRAL observations of the type 1.5 Seyfert galaxy NGC
4151. Combining several INTEGRAL observations performed during 2003, totaling
about 400 ks of exposure time, allows us to study the spectrum in the 2 - 300
keV range. The measurements presented here reveal an overall spectrum from
X-rays up to soft gamma-rays that can be described by an absorbed (NH = 6.9e22
1/cm**2) model based on a Compton continuum from a hot electron population (kT
= 94 keV) from an optically thick (tau = 1.3) corona, reflected on cold
material (R=0.7), consistent with earlier claims. The time resolved analysis
shows little variation of the spectral parameters over the duration of the
INTEGRAL observations. The comparison with CGRO/OSSE data shows that the same
spectral model can be applied over a time span of 15 years, with flux
variations of the order of a factor of 2 and changes in the underlying
continuum reflected by the temperature of the electron population (kT = 50 -
100 keV). When modeled with an exponentially cut-off power law plus Compton
reflection this results in photon indices ranging from Gamma = 1.5 to Gamma =
1.9 and a cut-off energy in the range 100 - 500 keV.
