The paper will describe the online measurement of thin and flat specimen changing during laser alloying and measurement of alloy specimen after treatment. SiC, Stellite 6 and Stellundum 481 powder were added separately into the parent metal of low-carbon steel during laser remelting and alloying. Experiments were performed with high-temperature strain gage rosettes. Strain was monitored from the beginning to the end of the remelting and alloying process, i.e., to a temperature of 50degreesC at the back side of the specimen; therefore, during the remelting and alloying process, the changes in temperature at the back side of the specimen were measured with two Ni-NiCr thermocouples. It was found that the magnitude of strain is affected by energy input and the direction by the mode of laser-beam movement. Three modes of movement of the laser beam with the same degree of overlapping and the same size of treated area will be represented. It is important for industrial applications of laser remelting and alloying to have specimens with the lowest strain since this means low cost of final grinding. Other very important properties are the size and distribution of the residual stresses in the thin remelting and alloying specimen, i.e., machine part, because they strongly affect its operational efficiency. The paper will analyze the results obtained from the viewpoint of minimum final strain of the specimen with the desired variation of residual stresses.