Objective: To describe the frequency and age at onset of abnormal echocardiograms in a cohort of patients with mutations in FKRP. Background: The dystroglycanopathies (DGs), caused by mutations in one of 18 known genes, are autosomal recessive muscular dystrophies that share hypoglycosylation of a-dystroglycan. The DGs range from severe congenital muscular dystrophy to limb-girdle muscular dystrophy. The largest subgroup of DGs results from mutations in FKRP (LGMDR9). Reported frequencies of cardiomyopathy in LGMDR9 are varied. Methods: All available echocardiogram reports and/or films done for clinical indications on participants in a DG natural history study (clinicaltrials.gov NCT00313677) with mutations in FKRP were collected and retrospectively reviewed. All echocardiograms were classified as normal (EF >55%; SF ≥ 28% for patients aged 15 years and older, 31-41% for patients aged 4-14 years, 33-43% for patients aged 2-3 years, and 35-45% for infants; normal wall motion) or abnormal. The probability of developing an abnormal echocardiogram was assessed by Kaplan-Meier analysis. Results: Of 269 echocardiograms on 56 subjects, at least one abnormal echocardiogram occurred in 25 subjects (44.6%). Median age at first abnormal echocardiogram for the whole cohort was 33.25 years (95% CI: 17.98, 54.21). Median age at first abnormal echocardiogram for subjects homozygous for the c.826C>A variant was 54.21 years (95% CI 39.67, 54.21) compared to median age for all other FKRP genotypes of 15.44 years (95% CI: 14.31, 18.06), p<0.0001. The earliest age at first abnormal echocardiogram was 3 years. There was no significant difference in cardiomyopathy onset by sex. Conclusions: Cardiomyopathy is prevalent in those with FKRP mutations. While the median onset is in mid-adulthood, it can present in childhood. Genotype influences age at onset; cardiomyopathy occurs later in subjects homozygous for the c.826C>A mutation. These data can help to guide surveillance frequency.