Neoclassical diffusion coefficients, D, are evaluated in an ℓ = 2 helical system with ∊h, ≳ ∊t by using the Monte-Carlo method as developed by Boozer and Kuo-Petravic, where ∊h and ∊t are the helical and the toroidal ripple, respectively. An elliptic deformation of the magnetic surface, d, introduces an additional ℓ= 1 helical ripple on the assumption of d ≪ 1. Numerical calculations show that D ∞ l/ν with a coefficient depending on d, where ν is the collision frequency. By adding an ℓ = 3 helical component with no substantial effect on neoclassical transport to the ℓ = 1 and ℓ = 2 helical fields, D ∞ (1+1.2d)/ν is obtained analytically, as a result of helically trapped particles. This will bring about an increase in D of 30–50%, as compared to the assumption of a circular averaged magnetic surface.