Between 1991 and 1999, 28 Nature Reserves and protected areas in the eastern side of South Africa were surveyed for geometrid moths (Lepidoptera: Geometridae).  The 510 species and subspecies that were found in these reserves are illustrated in colour and 1402 records of their occurrence in the 28 reserves is recorded.  The family Geometridae is briefly introduced.  The following new genus/specific name combinations are made: Mauna homales (Prout, L. B., 1922); Heterorachis roseifimbria mozambica Prout, L. B., 1930.  The status of the following taxa is reversed: Eupithecia rubidimixta Prout, L. B., 1916; Comibaena coryphata (Felder, 1875); Heterorachis roseifimbria Prout, L. B., 1930.  The reasons for the above taxonomic changes are given.