This report describes the first successful case of preimplantation genetic diagnosis (PGD) for myotonic dystrophy type Curschmann–Steinert (DM1) using polar body biopsy with vitrification. A 39-year-old woman with expansion of a CTG trinucleotide repeat in the DMPK gene was included into the study centre’s PGD programme. After intracytoplasmic sperm injection, a total of 13 fertilized oocytes were successfully biopsied for the first and second polar body. Nested multiplex polymerase chain reaction was used to amplify the CTG repeat region in DMPK along with two linked polymorphic markers. Six pronuclear stage (PN) oocytes were diagnosed as unaffected and four as affected by the CTG expansion, while analysis of the remaining PN oocytes was inconclusive. Three normal PN oocytes were left in culture to develop to cleavage-stage embryos and the remaining three were vitrified by applying the Cryotop method. On the following day, only one embryo was transferred into the patient’s uterus and the remaining two were vitrified because of the progressive threat of ovarian hyperstimulation syndrome. Since the fresh cycle did not result in a pregnancy, 6 months later the two vitrified cleavage-stage embryos were warmed and transferred back to the patient. A clinical pregnancy was established and a healthy boy was born following Caesarean section in week 39 of gestation.