The application of Giemsa technique to stain compressed diaphragm samples obtained from rodents experimentally infected with Trichinella spiralis is described. Diaphragm samples from rats heavily infected with 20 muscle larvae per gram of body weight(20 ML/gbw) were cut into several pieces and stained with Giemsa; on the other hand, whole diaphragms from slightly infected mice(1 ML/gbw) were also stained with Giemsa. Besides, muscle samples were also stained with Giemsa. Observation at 10 $ imes$ magnification revealed that both ML and nurse cells(NC) look as bluish structures clearly contrasting with the pinkish color of the non-infected muscle fibers. NC in the diaphragms of mice could be easily observed at naked eye as blue points contrasting with the pink surrounding areas formed by the non-infected muscle fibers. Among NC observed in the diaphragms of rats infected with 20 ML/gbw, 4.4% was multiple infection. These findings were confirmed in sectioned and hematoxylin-eosin stained specimens. This data could be usefulness for a rapid diagnosis of trichinellosis in post-mortem mammals without magnification procedures.