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The present paper aimed to experimentally investigate the effect of micro steel fibers (MSF) on the structural shear behaviour of SCC deep beams made of 100% RA. Flexural test were performed on six simply supported deep beams under a single-point loading scheme at shear span to effective depth ratio (a/d) of 1.2 and 1.5. Two SCC beams were made of natural aggregates (NA) without MSF, two beams were made of a 100% RA without MSF, and the last two beams were made of RA with MSF at a volume fraction (vf) of 1%. The parameters considered in this research included load deflection response, ultimate shear failure load, and cracking pattern. The obtained results indicated that using RA considerably reduced the shear capacity of reinforced SCC deep beams in comparison with control mix, and that reduction was more pronounced when a/d ratio was decreased. At a given shear load value, the deflection of RA-based beams was higher than that of NA-based beam, regardless of a/d ratio. This clearly reflected the inferiority of RA particles. However, a comparable or even superior shear strength can be reached when up to 1% MSF was added. Based on this experimental investigation, it was demonstrated that the crack patterns of SCC deep beams prepared with NA, RA, and even MSF, were generally identical. Nevertheless, the crack width for beams with a/d of 1.5 seemed to be more visible than that of a/d of 1.2. [ABSTRACT FROM AUTHOR]