Postexposure prophylaxis after sexual exposure to human immunodeficiency virus (HIV) is recommended by state and national agencies. A cross-sectional survey of 117 Los Angeles County sites found that 17 sites (14.5%) offer postexposure prophylaxis. Ten sites (8.5%) offer postexposure prophylaxis to patients who are uninsured. General availability of postexposure prophylaxis should be a public health priority.