Mississippi DNA & Drug Testing: Find Clinic Locations by City Drug Testing and DNA Testing Locations in Mississippi: Health Street has 65 Clinics in 27 MS Cities Bay Saint Louis Belden Biloxi Brookhaven Columbus D‘Iberville Flowood Greenville DNA Testing Greenville Drug Testing Grenada Gulfport Hattiesburg Jackson Laurel McComb Meridian Natchez New Albany Olive Branch Pascagoula Pearl Philadelphia Picayune Ridgeland Southaven Tupelo Vicksburg Waveland Marijuana Laws in Mississippi: THC is not permitted for any legal use in the state of Mississippi.