The main purpose of the present study was to evaluate the diversity and content of various phenolic compounds in floral infusions of 14 elderberry genotypes (3 species and 9 interspecific hybrids). Detailed phenolic analysis was performed using HPLC-MS. Hydroxycinnamic acids (HCAs) were the major phenolic group identified and 3-, 4-, and 5-caffeoylquinic acids were detected in infusions prepared from all analyzed species and interspecific hybrids. Several flavonols were identified in elderberry floral infusions: 8 isorhamnetin derivatives, 6 quercetin derivatives, 2 flavanones, and 6 kaempferol derivatives. The main flavonols detected in all samples were isorhamnetin-3-rutinoside, isorhamnetin dihexoside, quercetin-3-rutinoside, kaempferol-3-rutinoside, and kaempferol dihexoside. The highest levels of flavonols and hydroxycinnamic acids were measured in interspecific hybrid infusions of Sambucus javanica x S. cerulea, (S. javanica x S. nigra) x S. nigra cv. Black Beauty, (S. javanica x S. nigra) x S. nigra, and S. javanica x S. racemosa.