The degree-day method is one of the well-known and the simplest methods used in the Heating, Ventilating and Air-Conditioning industry to estimate heating and cooling energy requirements. In this study, the heating and cooling degree-days for Turkey are determined by using long-term recent measured data. Five different base temperatures ranging from 14 to 22 degreesC are chosen in the calculation of heating degree-days. In the case of cooling degree-days, 6 different base temperatures in the range 18 to 28 degreesC are used. Yearly heating and cooling degree-days are given both in tabular form and as counter maps for all the provinces of Turkey (78 weather stations). (C) 2001 Elsevier Science Ltd. All rights reserved.