In this article it is reported about 35 intraabdominal abscesses, which were sonographically diagnosed in 32 patients. 22 times the diagnosis could be proven with percutaneous fine-needle-aspiration guided by ultrasound, five of them had a sonographically guided percutaneous abscess drainage, while 7 only could be diagnosed by operation. The sonomorphologic criteria of intraabdominal abscesses are polymorphous. Therefore we could subdivide the abscesses into five types according to their different echogeneity. Probes of pus, won by percutaneous five-needle-aspiration, were examined under experimental conditions in a waterbath. The sonomorphologic appearance is comparable to the in-situ-situation. Our experiments showed, that the echogeneity of intraabdominal abscesses is based on echogenic microbubbles besides echoforming detritus and protein-bodies. The polymorphous sonographic appearance of intraabdominal abscess formation and the well known problems of differential diagnosis gives percutaneous, sonographically guided fine-needle-aspiration an important position.