The aim of this paper is the study of the modification of AlSi7Mg alloy with two types of master alloys: AlSr10 wire type and AlSr10 block type, at a temperature of 750degreesC with different contents of strontium. Due to the applicability of the AlSr10 master alloy wire type, the study was mainly elaborated on the dissolving process of this one. Due to this fact we used a 10 mill diameter wire of AlSr10 master alloy, which was introduced in the melt. After the grain refining process we obtained a sample, which was cut at different heights for a better observation of the alloy structure. We call notice that the grain refining degree is not uniform along the sample. Strontium as a grain refiner equalize the qualities oh sodium but is much more efficient and keeps its grain refining properties for a longer period of time. The efficiency of the two types of master alloys was compared by the grain refinement degree of AlSi7Mg alloy function of the distance till the lower part of the casting mould and by determination of the grain refinement degree function of strontium content added. We made a micrographic study of the pieces of the sample and we used all optical microscope (OLYMPUS BX 60M) and the image analyzing system was OMNIMENT EXPRESS. Analyzing the results of this study we call see that the AlSi7Mg alloy grain refining degree doesn't depend too much on the form of the master alloy (if is wire or block) but grain refining time is increased when we use block types of master alloy. Also we call see that the cooling rate has a significant influence on the grain refinement degree. The industrial application of the AlSr master alloys are mainly for the light alloys ingots producers and light alloys casting plant for the obtaining of high quality components required by automotive and aeronautical industry.