The results of transmission electron microscopy investigation of fine structure of FeGe2 single crystals are reported. The main defects revealed are edge dislocations, dislocation loops and stacking faults located predominantly in close-packed crystallographic planes. The spatial distribution of structural defects is shown to correlate with peculiarities of the growth technology. The dislocation density in the specimens studied is about 104cm-2 and is almost constant in a wide range of pulling speed. Small amounts of doping elements (Co, Al, Sn) do not change significantly the microstructure, so after growth parameters are corrected high quality crystals can be obtained anyway.