doktorski

1. (of a physician) doctor's; medical
   Ima pravi doktorski rukopis, ništa ne može da se pročita. — He has real doctor's handwriting, you can't read a thing.
   Bez doktorske potvrde ne možeš da opravdaš izostanak. — You can't excuse the absence without a doctor's note.
2. (of an academic degree) doctoral
   Sledeće godine brani doktorsku disertaciju. — Next year he is defending his doctoral dissertation.
   Upisala je doktorske studije u Beogradu. — She enrolled in doctoral studies in Belgrade.

In the medical sense, official language more often uses lekarski (lekarsko uverenje).