We have been performing preimplantation genetic diagnosis (PGD) since 1991. Three years ago we also introduced a programme of preimplantation genetic screening (PGS). The majority of our clinical research has been to develop single cell diagnosis for PGD and to develop an accurate method of analysing chromosomes for PGS. We are currently working towards laboratory accreditation. UCL Centre for PGD was one of the first centres in the world to offer PGD. Our clinical achievements include the first use of FISH for sex determination, one of the first clinics to use FISH for the diagnosis of chromosome abnormalities, first UK centre to offer PGD for myotonic dystrophy (second centre worldwide) and first centre to specialise in PGD for inherited cancers. Some of our team were involved in setting up the ESHRE PGD Consortium (Joyce Harper is currently Chair and Sioban SenGupta is on the steering committee). Our group were responsible for the only text book on PGD published in 2001, and Joyce Harper is editing another PGD book with CUP. We are often invited to international conferences to talk about PGD. We have run 12 hands on PGD workshops. For our research activities we were one of the first group to describe the level of chromosome abnormalities in human preimplantation embryos and the first to describe chaotic embryos. The majority of PGD clinics concentrate on clinical work but we are lucky to be able to study early human development in detail.