Cilj. Cilj istraživanja je procijeniti podudarnost veličine rezidualnog tumora, izmjerene magnetskom rezonancijom (MR) i patohistološkom dijagnostikom (PHD) u pacijentica s karcinomom dojke nakon provedene neoadjuvantne kemoterapije (NAK) te procijeniti mogući utjecaj ypT stadija tumora na nepodudarnost veličina izmjerenih navedenim metodama. Ispitanici i metode: U retrospektivno istraživanje uključeno je 50 pacijentica. Uključni kriterij su pacijentice kod kojih je učinjen operativni zahvat uz prethodno proveden NAK karcinoma dojke, na što je odgovor praćen s najmanje dva MR pregleda. Veličina tumora na MR-u uspoređena je s veličinom na PHD-u (zlatni standard) pomoću regresijske analize Passing-Bablok te je izračunat njihov koeficijent korelacije. Analizirana su sva odstupanja i podudarnosti veličine, kao i eventualni utjecaj ypT stadija tumora na razliku između dviju metoda. Razlika od ± 0,5 cm u veličini tumora procijenjenih slikovnom metodom i u PHD nalazu smatrale su se podudarnima veličinama. Rezultati: Srednja vrijednost veličine rezidualnog tumora na MR-u iznosila je 19,1 ± 17,71 mm, dok je na PHD-u iznosila 16,87 ± 18,19 mm. Izračunati r koeficijent korelacije iznosi 0.64 (p <0.001). Provedenom analizom potvrđeno je da nema značajne razlike izmjerenih veličina tumora na MR-u i PHD-u (p = 0.552) te se metode mogu smatrati podudarnima. Nije uočena statistički značajna razlika u ovisnosti o ypT stadiju tumora koja bi utjecala na nepodudarnost veličina. Zaključci: Među dvjema metodama nema konstantnog niti proporcionalnog odstupanja u mjerenjima te se metode mogu smatrati podudarnim. MR dojke je dobra metoda za procjenu veličine rezidualnog tumora dojke kod pacijentica koje su podvrgnute neoadjuvantnoj kemoterapiji usporedno s PHD-om (zlatni standard).; Aim: The goal of this study is to evaluate the concordance between residual tumour size measured on magnetic resonance imaging (MRI) and pathohistological findings in patients who underwent neoadjuvant chemotherapy and operative procedure, and if any pathohistological features may affect that agreement. Respondents and methods: Fifty patients with breast cancer were retrospectively evaluated. Patients who underwent neoadjuvant chemotherapy before the operative procedure, and were assessed with at least two MRI examinations, where included in this study. The primary tumour size measured by MRI was compared with pathohistological findings, which was considered as the gold standard. All differences and size correspondence were analyzed as well as the possible influence of ypT stage of tumour between the two methods. Results: The mean value of residual tumour size on MRI was 19,2 ± 17,71 mm, while on pathohistological findings it was 16,87 ± 18,29 mm. A calculated correlation coefficient between the two methods was 0.64 (p <0.001). There was no statistically significant difference between two methods for measuring residual tumour size (p = 0.552), as well as a statistically significant influence of ypT stage on measuring, so these methods may be considered to be concordant. Conclusions: There is neither a constant nor a proportional deviation in the measurements between the two methods, so these methods can be considered concordant. Breast MRI is a reliable method for estimating residual tumour size in patients undergoing neoadjuvant chemotherapy in comparison to pathology.