We studied low frequency power spectral density (PSD) of drain current, I_d, fluctuations in organic materials field effect transistors, (OMFETs), with pentacene and polytriarylamine channels and analyzed the data using parameters extracted from I_d(V_g) characteristics, following a procedure developed for Si MOSFETs. We found that PSD spectra (i) vary as 1/f, (ii) show I_d^a ,with α≈2, amplitude variation, and (iii) scale with the gate surface. That provides some elements for constructing a model for noise generation in OMFETs and for normalization of PSD data. We show that normalized noise amplitude in OMFETs can be up to 10³ times higher than in their Si counterparts.