Abstract: Chromosome numbers are reported for the first time for 303 individuals of 112 taxa and cultivars and five hybrids from 16 genera, nearly all from eastern Canada and the eastern United States. Counts for several taxa from China, Japan, the United Kingdom and for several garden cultivars of Old World taxa are reported. Also included are seven corrections and changes of identifications for previously published reports for taxa in Solidago. The majority of the reports are for asters listed in this paper under the generic name Symphyotrichum (including Virgulus) plus species of Aster (including Asteromoea, Diplactis, and Kalimeris), Callistephus, Doellingeria, Eurybia, Galatella, Ionactis, Ocletnena, and Sericocar pus, and for goldenrods in Solidago and Euthamia. The following are first reports for the taxa: Aster pyrenaeus cv. "Lutetia", 2n = 36 + 2-4 supernumeraries, cult. Ontario; Solidago altiplanities, 2n = 18 from Texas; S. arenicola, 2n = 36 from Alabama; S. glomerata 2n = ca. 126 (14x) from North Carolina; S. speciosa subsp. pallida, 2n = 18 from South Dakota; Symphyotrichum plumosum, 2n = 8 (two populations) from Florida; and S. tradescanti, 2n = 32 from Maine. All other counts confirm previous reports for the taxa. A number of the reports are for rare taxa in Ontario: Solidago arguta, 2n = 18, first count for Ontario; Symphyotrichum praealtum var. praealtum, 2n = 32; S. prenanthoides, 2« = 32, first counts for Ontario (8 populations); and S. shortii, 2n = 16. A number of the counts are first reports for a particular taxon in a state (e.g., Solidago altissima subsp. altissima, 2n = 36 from Tennessee; S. brachyphylla, 2n = 18 from Florida; S. canadensis var. hargeri, 2n = 18 from Virginia; Symphyotrichum novae-angliae, 2n = 10 from Georgia and North Carolina; S. priceae, 2n = 64 from Georgia). Differences in the karyotypes of Old and New World species of asters are discussed.