Rutile crystals of controlled composition have been grown from Na2O·3B2O3and K2O·3B2O3fluxes. The compositions were controlled by the use of various atmospheres of known oxygen activity as the equilibrium vapor phase. The crystals are prisms 2 to 10 mm in length and 0.1 to 0.3 mm in thickness. The morphology of the crystals and their response to changes in temperature, oxygen activity, and flux composition are described. The average dislocation density is 4×104cm−2, but dislocation‐free areas can be found.