Temporal myositis is a rare inflammatory disease of the temporal muscle. We report a case of unilateral temporal myositis, in which a polymyositis was diagnosed two years thereafter. Although focal myositis may rarely herald polymyositis, isolated temporal myositis preceding inflammatory myopathies has not been described, to our knowledge. In the setting of a temporal pain and swelling, ultrasonography may help in diagnosis, biopsy guidance, disease extension, and progression assessment. Further studies are necessary to establish the role of elastography in differentiating between muscle inflammation and hypertrophy.