Single crystals of magnesium fluoride, grown by the Czochralski technique, have been examined by means of chemical etching, and optical and electron microscopy. Dislocations in as‐grown crystals are found to be decorated with precipitates; the nature of the precipitates has been investigated. Grown‐in dislocations and undecorated dislocations introduced by slip can be etched in hot sulfuric acid. Etch pits at grown‐in dislocations often exhibit characteristic ``beaks'' or ``tails.'' Chemical etching has been used to establish the existence of three slip systems, namely {110}⟨001⟩, {001}⟨100⟩, and {101¯}⟨101⟩.Specimens for examination by transmission electron microscopy were prepared by chemical dissolution after mechanical shaping. Grown‐in dislocations are normally removed by unavoidable selective etching. In the microscope the samples are damaged by the electron beam. Point defects are produced which aggregate and result in both dislocation loops and precipitate platelets.