The realization of an all-solid microstructured optical fiber based on chalcogenide glasses was achieved. The fiber presents As2S3 inclusions selected as low refractive index material (n = 2.4) embedded in a As38Se62 glass matrix (n = 2.8). The single mode regime of the fiber was demonstrated both theoretically by multipole method calculations and experimentally by near field measurements. Optical transmission measurements of the microstructured fiber and single index fibers made of the initial glasses reveal an excess of losses as high as 6-7 dB/m. This excess is not due to the guide geometry but can be explained by the presence of defects in the glass interface regions.