According to Article 15 of the Labour Law No: 4857, trial period for labour contracts may not exceed 2 months. 
Within this trial term, parties may terminate the employment contract without having to observe the notice period or without having to pay compensation. The employee becomes entitled to wages and other rights for the days worked under this trial period.
Parties are not obliged to demonstrate any reasons for termination within this trial period.
After the expiration of the trial period, a party who wishes to terminate the contract shall observe the relevant rules of Labour Law, depending on the nature of the contract (e.g.: employment contract for indefinite period or definete period)