Androctonus tenuissimus sp. n. from two coastal localities placed in northwestern Egypt is herein described, an addition that represents the fifth species of this genus confirmed to occur in this North African country. It is most closely related only to Androctonus bicolor Ehrenberg, 1828, which is widely distributed across northeast Africa and the Middle East and also occurs in Egypt. Both are the only species in the genus whose adults of both sexes show the following combination of three diagnostic characters: coloration uniformly blackish, pedipalp chelae con-spicuously narrower than patella in adults, and pedipalp fingers with basal lobe/notch combination entirely absent. However, these two taxa can readily be distinguished by very marked differences in appendage attenuation, body sculpture and counts of principal rows of denticles on pedipalp fingers, among other characters.