Parapat is a small town on the edge of Lake Toba.
From Medan there is a local bus (no air-con) about every hour for 22,000 rupiah (Oct 08) if you pay on the bus. The journey takes 4-6 hours, depending on the traffic condition.
will pick you up at the airport. Scheduled runs in an Toyota Inova (5 seaters vehicle) will cost you 100,000 IDR per person (Feb, 12). Alternatively, you can book the whole car or private van for 500,000 IDR. And sometimes if you had afternoon flight from Medan (02.00 - 05.00 PM), could not be reach the last boat to Samosir Island (the famous destination), whom schedule for the last boat at 06.00 PM; Tobatransporter could be help you to stay in their guest house in Parapat (stay over night, 100.000 IDR/r/n); and tomorrow morning get the first boat to Samosir Island at 08.30 AM.
There is public bus every hour to Medan; 22,000 per person (not air conditioned). Other options by Taxi Trans like Paradep Taxi or Tobatransporter and Raja Taxi who run the time schedule every hour; destination to Medan for 5 seaters share taxi(100,000 IDR/person) , Bukit lawang (170.000 IDR/person); Berastagi (120,000 IDR/person); just made a reservation by call or SMS +6285261492668 or [firstname.lastname@example.org]; for 7 seaters share taxi is: Medan (75.000 IDR/person); Bukitlawang (150,000 IDR/person); Berastagi (100,000 IDR/person)