Drive south on U.S. 19
Take the ramp for Sr-611 South / 49th Street North towards Pinellas Park
Merge onto 49th Street North
Northside Hospital will be on your right, after the railroad tracks
 

From Southern Pinellas County:

Drive north on U.S. 19
Turn left at 54th Avenue North
Turn right at 49th Street North
Northside Hospital will be on your left, before the railroad tracks

From Tampa:

Drive south on I-275
Take exit 28 for FL-694 West towards Pinellas Park
Turn left at 49th Street North
Northside Hospital will be on your right, after the railroad tracks