Ventricular septal defect (VSD) is one of the most common congenital heart defects in cats. It usually occurs as a single defect, but in rare cases it may be part of a complex defect. Echocardiography is a method that affords a reliable and non-invasive diagnosis of VSD. The objective of this study was to determine the incidence and type of ventricular septal defects (VSD) in a feline population over six years of follow-up. The study analyzed VSD incidence in 31 cats from the Department of Epizootiology and Clinic of Infectious Diseases, University of Life Sciences, Lublin, between January 2018 and December 2023. VSDs were classified into four groups by Soto. All 31 cats (13 males, 18 females), aged 2 months to 4 years, had normal basic biochemical panels. Clinical examinations detected heart murmurs in all cats, with 14 showing signs. Echocardiography assessed cardiac function and VSD flow. Statistical analysis examined correlations between the type of VSD, clinical signs, breed and sex, without age correlation. The study found no significant breed predisposition for VSD, although mixed-breed cats were diagnosed most frequently. Nor was there any significant correlation between the type of VSD and the cats’ sex. The severity of clinical signs correlated with the location and size of VSD. The findings demonstrate the importance of routine echocardiographic screening to detect VSDs early, potentially improving therapeutic outcomes and the quality of life of affected cats.