It has been demonstrated in three chilling-sensitive species (Capsicum annuum L., Lycopersicon esculentum Mill., Solanum melongena L.) that improvement of chilling tolerance may be induced by continuous lighting (CL) without low temperature treatment and the acquisition of this chilling tolerance was related to proline. The results suggest that induction of plant tolerance to unfavourable temperature by absorption of excess light by plants can occur not only under high-intensity light as shown in several studies, but also due to increasing of the daily light integral by extending the photoperiod. The improvement of chilling tolerance induced by CL without cold treatment occurs to a lesser degree than when induced by low temperature (2 h temperature drop to 10 C in the end of the night).