Egg capsules and intracapsular embryos of Rapana venosa were studied to determine the reproductive pattern of this invader species in the soutli-eastern Black Sea. Egg deposition of R. venosa in the laboratory at 25 degrees C was described. Egg laying began in mid-June, reached a peak in July and ended in late August in 1996. The total number of the egg capsules per whelk ranged between 197 and 999 (mean 575 +/- 41). The mean length of the egg capsules was 13.26 mm. Each capsule contained between 124 and 1090 embryos with a mean of 555 +/- 10. M,lean larval production per rapa whelk was about 392,931 +/- 42,731. The mean size of eggs produced was 213.8 mu m. Five different stages of intracapsular development were observed. Embryos developed without nurse eggs. Veliger larvae completed their intracapsular development and hatched in 22 days at 25 degrees C.