Forty-two difficult-to-cultivate group A coxsackieviruses (i.e., group A types other than A7, A9, and A16), collected primarily from throat swab specimens of patients suffering from fever, pharyngitis, lymphadenopathy, and cough during the 1986 enterovirus season, were isolated in less than 24-h-old suckling mice. Thirty-six moribund mice were sacrificed and autopsied, and then their brains and back musculature were inoculated into rhabdomyosarcoma (RD), guinea pig embryo (GPE), rhesus monkey kidney (RhMk) and human carcinoma of the larynx (HEp-2) cell cultures. Twelve of the 36 suckling mice isolates were adapted to grow in RD and GPE cells after two passes and have been identified in RD cells by type-specific antisera as group A coxsackievirus types A2, A4, and A8. Three passes in RhMk or HEp-2 cell cultures were insufficient to affect a discernible cytopathic effect. Coxsackievirus types A1, A19, and A22, unable to grow in any of the four cell cultures tested, were identified by virus neutralization in suckling mice. These data denote the efficacy of suckling mice for the isolation of difficult-to-cultivate group A coxsackieviruses.