The properties of InAs epilayer grown on (001) InP substrates (oriented 2° off (001) toward the  direction) using meta-organic chemical-vapor deposition (MOCVD) are reported. The epilayer of 17 nm thickness grown at 405 °C showed three kinds of misfit dislocation arrays. Their Burgers vectors in all cases were of the form a/2〈101〉 inclined 45° to the interface. Upon annealing 600, 140 and 220 nm InAs epilayers at 660 °C, most misfit dislocations became Lomer-type oriented exactly along the 〈110〉 direction. Average distance between misfit dislocations at early stage of growth was inversely proportional to the InAs thickness. This phenomena was interpreted to the relationship between the dislocation interaction energy and residual InAs epilayer strain energy.