  Nonlinearity introduced in slow-roll inflation will produce weakly
non-Gaussian CMB temperature fluctuations. We have simulated non-Gaussian large
scale CMB maps (including COBE-DMR constraints) introducing an additional
quadratic term in the gravitational potential.The amount of nonlinearity being
controlled by the so called nonlinear coupling parameter f_{nl}. An analysis
based on the Spherical Mexican Hat wavelet was applied to these and to the
COBE-DMR maps. Skewness values obtained at several scales were combined into a
Fisher discriminant. Comparison of the Fisher discriminant distributions
obtained for different nonlinear coupling parameters with the COBE-DMR values,
sets a constraint of abs(f_{nl})<1100 at the 68% confidence level. This new
constraint being tighter than the one previously obtained by using the
bispectrum by Komatsu et al. (2002).
