Background: In commercial almond [Prunus dulcis (Mill.) D.A. Webb] orchards in Chile, the percentage of fruit set 16 is low and commonly reaches 5–30%. As almond trees bloom during a cool period and also suffer from 17 self-incompatibility, any factor that can improve pollination, pollen germination and pollen tube growth or 18 extend the effective pollination period, such as the application of plant bioregulators (PBRs), should be 19 beneficial for fruit production. 20 Results: Three plant bioregulators (PBRs): brassinolide (BL), gibberellic acid (GA3) and kinetin (KN) were 21 evaluated for pollen germination and pollen tube growth in vitro, as well as for fruit set in almond cultivars 22 Non Pareil and Carmel, in central Chile, during the 2013 and 2014 seasons. For pollen germination in vitro, the 23 BL concentration of 10 mg L-1 had the highest value in Non Pareil (97.7%), after 4 h germination in 2014 24 growing season (the control was 90.9%). KN at a concentration of 50 μL L-1 induced the longest pollen tube 25 growth of 1243.4 μm in Carmel after 8 h germination in 2013 (the control was 917.7 μm). In Non Pareil, the 26 highest percentage of fruit set (31.0%) was achieved in 2014 by spraying during bloom at pink bud stage with 27 KN at 50 μL L-1 (the control was 16.7%). 28 Conclusions:AsignificantfavorableeffectofthetestedPBRswasobservedinpollengerminationandpollentube 29 growth in vitro, as well as on fruit set in Non Pareil and Carmel almonds.