On November 18, 2024, The Centers for Disease Control and Prevention (CDC) issued a Health Alert Network (HAN) Health Advisory to provide information about the first case of clade I mpox diagnosed in the United States and recommendations to clinicians about preventing, diagnosing, treating and reporting mpox cases. On November 15, 2024, the California Department of Public Health (CDPH) confirmed the first reported case of clade I mpox in the United States. This individual had recently traveled to areas experiencing clade I monkeypox virus (MPXV) transmission and sought medical care for mpox symptoms in the United States. Consistent with other recent clade I mpox cases, the patient has relatively mild illness and is recovering. CDC and the local and state health departments are investigating potential contacts; no additional cases in the United States have been detected as of November 18, 2024. The risk of clade I mpox to the public in the United States remains low.