The average bit-error-rate, ⟨ BER ⟩ , of optical wireless system using higher order mode laser beam is investigated when atmospheric turbulence shows anisotropic and non-Kolmogorov characteristics. Results reveal that increase in anisotropy in both x- and y-directions positively affects the optical wireless systems performance. Increase in the beam order results in an increase in ⟨ BER ⟩ for any anisotropy level, and thus, higher order beams adversely affect the optical wireless systems performance. Larger structure constant, beam source size, and propagation distance result in larger ⟨ BER ⟩ , but larger wavelength, inner scale length, and signal-to-noise ratio tend to reduce ⟨ BER ⟩ . Increase in the power-law exponent of non-Kolmogorov turbulent spectrum first increases the ⟨ BER ⟩ until a certain value, and then ⟨ BER ⟩ starts to decrease when the power-law exponent is further increased. Adverse effect of higher order laser beam holds to be valid for any power-law exponent of non-Kolmogorov turbulence.