The changes in chlorophyll fluorescence parameters and in male gametophyte caused by high temperature (HT) were studied to determine a suitable regime to test the heat tolerance of Capsicum annuum genotypes. The plants (cv. Bial Kalinkov) were grown in a glasshouse in 5 L plastic pots on a commercial soil-peat substrate. Whole plants were treated with HT (35o, 40o and 45oC for 1, 2, 3, and 4 hours) in the bud formation-blossoming stage. It was established that the applied HT regimes influenced the pepper plants to varying extent. We concluded that: temperature values of 35oC and 45oC are not suitable to screen test pepper lines and varieties to heat tolerance; the male gamethophyte is more sensitive to HT stress compared with the photosynthetic apparatus; a semi-lethal effect on the male gamethophyte of pepper plants from the model cv. Bial Kalinkov was manifested at 40oC for 2 and 3 hours; the changes of the chlorophyll fluorescence parameters are better expressed at the higher values of HT regimes (40oC and 45oC for 2 and 3 hours); a suitable temperature regime to screen-test the heat tolerance of pepper species includes 40oC and duration of 2 or 3 hours.