INTRODUCTION: Obliteration of processus vaginalis (PV) has been proposed to result from persistence of smooth muscle which is presented transiently to propel the testis. Sacs associated with inguinal hernia were cultivated to define the cells that are going to proliferate for evaluating the association of inhibition of obliteration of PV and the presence of smooth muscle (SM). The present study does not only provide additional information about the presence of SM in sacs from boys with inguinal hernia, but also provides a new tool for researches directed to define the non- operative treatment of inguinal hernia