Abstract
Three newly isolated strains of Streptomyces phages have been examined by electron microscopy using the negative-staining technique. These phages have polyhedral heads and noncontractile tails ending in a clearly distinct fixation structure. They differ in their dimensions, head outline, flexibility of the tail and type of fixation plate. Some of their characteristics are new in the group of actinophages but correspond to known structures in other phage groups.