The first hyperpolarizability beta of n-alkanamides of 4-amino-N-(thiazol-2-yl)benzesulfonamide (A) and 4-amino-N-(pyrimidin-2-yl)benzenesulfonamide (B) was evaluated by ab initio (Gaussian, GAMESS) and semiempirical (INDO1/S) calculations. The results obtained at the ab initio level showed that the values of beta of the chromophores were 3.5-4 times that of p-nitroaniline. The calculations by INDO1/S gave preference to A and in absolute scale the beta values were 104.6 and 90.9 x 10(-40) m(4)/V for A and B, respectively, and they were slightly lower than those from ab initio. Fluorescence solvatochromism and hyper-Rayleigh scattering (HRS) was applied to determine experimentally the first hyperpolarizability of two amphiphiles containing n-hexadecanoyl (A) and n-decanoyl (B) radical. The values of beta obtained by the fluorescence solvatochromism were in the same range for A and B, and were (94-100) x 10(-40) m(4)/V while the HRS procedure gave preference to B yielding 252.1 and 197.8 (at 1064 nm), and 113.1 and 88.8 (static) for B and A, respectively (all in x 10(-40) m(4)/V). The role of the heterocyclic ring of the chromophore molecule in the electron donating-accepting process was shortly discussed.