An experimental investigation is presented to verify some theoretical results on the existence of two classes of modes (whispering and bouncing modes) in elliptical step index fibers. By utilizing a technology previously developed, silica plastic fibers with quasi elliptical cross section have been fabricated. The used noncircular preforms have been obtained by machining the circular cross section rods with a CO2 laser. The near field measurements performed on fibers with different ellipticity are interpreted on the basis of the theoretical results.