Abstract: Thiazolinone analogues of indolmycin having anti-viral activity as well as a degree of antibacterial and antimycoplasmal activity in contrast to the known indolmycin which has only some antibacterial activity. Tautomers and a single enantiomer or mixture of enantiomers are included. Intermediates are described which are cyclized to produce the active antiviral substances. Suitable dosage forms and amounts are set forth and various routes of administration included including administration to the respiratory tract as by insufflation or inhalation.