Perizoma obsoletata (Herrich-Schäffer, 1838) is shown to be a part of the Balkan fauna. Pabulatrix pabulatricula (Brahm, 1791) is new for the Western Balkans. One genus and 12 species are new and 20 species are reported for the second time for Albania. For Montenegro, one genus and eight species are new and two species are recorded for the first time. One genus and four species are new for the Republic of North Macedonia and another five species are reported for the second time from that country. One genus and three species are new for Bosnia and Herzegovina. Four species are reported for the second time and two for the third time for Serbia. Localities for Charissa pfeifferi (Wehrli, 1926) in Bulgaria are recorded for the first time. Data for some other interesting species from these countries and Greece are also presented. Most specimens were collected at light in 2019. Illustrations of specimens and their genitalia are given when necessary. Everted vesicas of some Geometridae species are illustrated for the first time.