Under laboratory conditions the effectiveness of four different insecticides (Neem Azal T/S, SpinTor, Neudosan Neu and Spruzit) to control onion thrips Thrips tabaci Lindeman on cucumber leaves (Cucumis sativus L.) of the cultivar Korinda F1 was investigated. The direct toxicity of several insecticides to the second larval stage was tested on leaf discs. The development of thrips larvae to prepupa and the feeding, survival and oviposition rate of T. tabaci females were examined on insecticide-treated cucumber leaf discs. Generally can be said that SpinTor (active ingredient spinosad) revealed the best effect on T. tabaci in all experiments, because 24 hours after the spinosad treatments all larvae and adult females were dead. Although the treatment of larvae with Spruzit (pyrethrins and rapeseed oil) caused a mortality rate of 30% 24 hours after spraying, the probability of larval survival on Spruzit treated leaf discs was 48% after five days. Seven days after the Spruzit treatment 40% prepupa were determined. The feeding and oviposition activity could be reduced by about 50% in comparison to the control variant (water). A similar reduction of feeding and oviposition rate were detected on sprayed leaf discs with Neudosan Neu (potash soap) or Neem Azal T/S (azadirachtin). Neudosan Neu and Neem Azal T/S caused an average toxicity of 4% 24 hours after treatment. Compared to Neudosan Neu (40%) the probability of survival of the larvae on Neem Azal T/S treated leaves was reduced to 14% five days after the treatment and 10% prepupa were determined after this period. The development of the larvae to the prepupa was mostly delayed with Neem Azal T/S. In summary the experiments showed, that SpinTor has the best and Spruzit an adequate effect against T. tabaci on cucumber.