Nine species of Crossopalpus Bigot, 1857 (Diptera: Hybotidae) have been found recently in Morocco. Four species new for science are described: Crossopalpus favipes Grootaert et Zouhair, sp. n., C. favitibia Grootaert et Zouhair, sp. n., C. nigritelloides Grootaert et Zouhair, sp. n. and C. undulans Grootaert et Zouhair, sp. n. New data and extended diagnoses on previously described species are provided for Crossopalpus aeneus (Walker, 1871), C. atlanticus (Rafone, 2015), C. dilutipes (Strobl, 1906), C. nigritellus (Zetterstedt, 1842) and C. setiger (Loew, 1859). New species-groups of Crossopalpus are proposed here for the frst time. All species are fgured based on specimens from Morocco to allow comparison with specimens from Europe. Crossopalpus pilipes (Loew, 1859) expected but not yet recorded from Morocco is illustrated based on a specimen from Romania. A key to the Moroccan species of Crossopalpus is also provided