Salicylic acid is one the numerous phenolic compounds found in plants with effects on different physiological and biochemical processes. We evaluated the effect of adding salicylic acid to a modified DKW liquid medium during the in vitro proliferation phase and ex-vitro acclimatation phase under controlled environmental conditions in a greenhouse. We used 12-14 mm shoots of the cultivar ‘Tonda Gentile delle Langhe’ hazelnut maintained in a modified DKW proliferation media (Driver and Kuniyuki, 1984) with supplements (with mg L-1: BA 1, IBA 0.01, pyridoxine 0.5, myoinositol 100, glycine 2, thiamin 1, nicotinic acid 0.5 and g L-1: saccharose 30, PVP 1.0 mg L-1 MES 0.5 g L-1) at pH 5.8. The proliferation experiment was performed on modified DKW media supplemented with different concentrations of salicylic acid. During the proliferation phase, the shoots were maintained at 16-h photoperiod and 3,000 lx. The best proliferation occurred in the control treatment without salicylic acid (6.13). The lowest proliferation rates were obtained for the salicylic acid treatments. Of the salicylic acid treatments, the lowest concentration (10 mg L-1) showed the highest proliferation rate (5.2) and the highest concentration showed the lowest. The greatest shoot length was in the 10 and 25 mL L-1 treatments. The greatest leaf length was at 10, 25 and 50 mg L-1 salicylic acid, with no differences among them. The shortest leaf length (1.40 cm) was in the 100 mg L-1 salicylic acid treatment. For shoot weight, the highest value was at 10 mg L-1 salicylic acid. The SPAD index was higher for all salicylic acid treatments compared to the control.