Gonads and accessory ducts of 140 live, captive-raised juvenile Erymnochelys madagascariensis (72–375 g body mass) of 1–3 years of age as well as those of some wild, larger turtles were investigated by endoscopy. The gonads of all examined turtles could be visualized by endoscopy and unambiguously identified as testes or ovaries. Of the captive-raised juveniles, 75% were females and 25% males. One-year-old females have small, thin, transparent ovaries with transparent, whitish follicles and thin oviducts. Follicles in 2-year-old females increase in number and appear as transparent, whitish flat discs and the oviducts become broader and transparent-whitish to whitish. Three-year-old females have yellowish-whitish follicles and whitish oviducts. Juvenile females over 0.5 kg body mass have yellow follicles and white oviducts. A 1-year-old male and 2 small 2-year-old males show testes of rose pink-whitish color and transparent epididymes. Other 2-year-old males have yellowish-orange testes and in males > 130 g body mass, the epididymes turn transparent-whitish. Three-year-old males have yellow-orange testes that are thicker and rounder, and whitish epididymes with meandering ducti epididymides. The developmental changes of juvenile reproductive tracts seem to depend more on age than on size.