Gastric emptying was evaluated in 11 male children (mean age 8.2 +/- 3.2 years) with progressive muscular dystrophy to detect gastrointestinal smooth muscle involvement. No patient had gastrointestinal symptoms. Gastric emptying studies were performed by using 500 microCi of technetium 99 m sulfur colloid bound to a scrambled egg, and scintigraphic measurements were taken continuously for 60 to 90 minutes. The gastric emptying studies were compared with those of eight male children (mean age 8.2 +/- 2.8 years) without gastrointestinal or muscular disorders. The mean percentage of retention of gastric isotope was significantly greater in the study group than in the control group. These data suggest that dysfunction of the smooth muscle of the upper gastrointestinal tract is detectable in children with progressive muscular dystrophy, even when gastrointestinal symptoms are absent.