The study was carried out to examine the photosynthetic efficiency of Scot pine populations, originated from various European countries and Anatolia in Turkey, exposed to UV-B radiation. Seeds were germinated and grown in the nursery; three-year-old seedlings were exposed to UV-B for two days, eight hours per day. The photosynthetic efficiency was probed by chlorophyll a fluorescence at 24 h after UV-B treatment and analysed by JIP-test. UV-B caused reduction in quantum yields and electron transport at both donor and acceptor sides of photosystems. The performance indexes of seedlings were also negatively affected by the treatment. Populations from France, England, and three provenances of Turkey showed sensitive responses, while the populations from Spain, Romania, and Ilgaz performed their photosynthesis better. We found that UV-B affected at different levels the photosynthetic functionality of populations. Chlorophyll a fluorescence technique is very useful to identify the UV-B tolerance of different Scots pine populations, however, further studies based on molecular analyses should be applied to explain their evolutionary history.