The paper contains the results of a non-destructive laser ultrasound internal structure analysis made on specially prepared friction stir welded joints made of aluminum samples. The process was conducted using four different groups of welding parameters. Different tool rotation speeds and tool traverse speeds were used. The main purpose of the research was to analyze the joint quality using a non-destructive laser amplified ultrasound method. A microstructure analysis was also conducted to compare the results of both tests.