Introduction HER2 receptor expressing breast cancers are aggressive with poorer prognosis. They can be determined via immunohistochemistry(IHC) or in situ hybridisation(ISH). IHC score 2+ and 3+ need confirmatory test by ISH for HER2 gene amplification prior to starting trastuzumab therapy. Trastuzumab improves both disease free survival(DFS) and overall survival(OS).However this drug is expensive , limiting its access to many patients. Methodology Analysis of female breast cancers with IHC score 2 and 3 (n=234 )were performed to determine the concordance with final ISH test for HER2 gene amplification. The HER2 positive tumors by ISH ( n=97) were analysed for access to trastuzumab. A Kaplan-Meier curve were produced to compare survival outcome between trastuzumab(n=20) and no-trastuzumab(n=77) group. Results Our concordance rates between IHC score 2+ and 3+ and ISH were 20.2% and 89.6% respectively. Among HER2 amplified tumors, only 15.7% received trastuzumab and after a mean duration of 19 months from diagnosis. The 5-year overall survival was higher for trastuzumab group (76% vs 52%) (log rank test p = 0.05). The hazard ratio for trastuzumab group was 0.264 ( 95% CI 0.063 -1.115 ). Conclusion Our concordance rate for IHC score 2+ and 3+ were comparable with other centres, although IHC score 3+ concordance with ISH could be improved to achieve a target of more than 95%. Access to trastuzumab was still very limited in our centre with a delay in therapy commencement. Similar poor access to this expensive drug were seen at other centres in Malaysia and other high middle income countries. The 5-year overall survival rate was higher for those who received trastuzumab , although not statistically significant due to small sample size. The higher OS and DFS were already established , for patients receiving trastuzumab from many RCTs , meta analyses and systematic reviews. Access to trastuzumab needs to be addressed urgently in Malaysian public hospitals for these HER2+ poor prognosis breast cancers.