We report a fetus with mosaic trisomy 11 who also had bilateral renal agenesis. We describe the post-mortem examination findings in the fetus and cytogenetic analysis. There are no earlier reports of full trisomy 11, presumably because it is lethal and results in early spontaneous miscarriages. There is only one report published earlier in a fetus with mosaic trisomy 11. There have been a few case reports of trisomy 11 identified in pre-natal samples, where it was associated with normal outcome. Bilateral renal agenesis has not been reported earlier in association with mosaic nor non-mosaic trisomy 11. We describe this rare cytogenetic finding in a fetus with bilateral renal agenesis. We also discuss the issues around genetic counselling when this is encountered in clinical practice.