['Severe tracheomalacia is a life-threatening disease, but symptoms usually improve with growth. The aims of this study were to investigate how slow release basic-Fibroblast Growth Factor (b-FGF) acts on tracheal cartilage, and whether growth-promoted trachea is more resistant against an increase in externally-applied pressure.', 'Biodegradable gelatin hydrogel sheets soaked in 10 μl of distilled water (sham) or 0.5 or 5 μg/10 μl of b-FGF solution were inserted behind the cervical trachea of three-week-old male Wistar rats. The cervical trachea was harvested 4 weeks later. Extratracheal pressure was increased from 0 to 40 cmH2O in a chamber, while video-recording the internal lumen. The luminal area at each pressure was expressed as a proportion to that at 0 cmH2O. The amounts of collagen type II and glycosaminoglycan were measured by ELISA.', 'The luminal areas at 40 cmH2O in the control (no intervention), sham, and each of the b-FGF groups were 0.65, 0.62, 0.72, and 0.73, respectively. The amounts of collagen type II and glycosaminoglycan in each group were 127, 136, 193, 249 μg/mg, respectively, and 15, 16, 19, 33 μg/mg, respectively. There were significant differences between the control group and the FGF 5 group (P=0.02, 0.01, 0.01, for luminal area, collagen, and glycosaminoglycan, respectively).'] Does slow release of basic fibroblast growth factor ( b-FGF ) enhance mechanical properties of rat trachea?