As a result of the Human Papillomavirus (HPV) vaccination program, the prevalence of precancerous dysplasia and invasive cervical cancer has substantially decreased. In this brief report, we present a case of a young patient who was diagnosed with in situ adenocarcinoma of the cervix. This 30-year-old female had completed the HPV vaccination after she became sexually active and has been undergoing annual gynecological assessments, including clinical examination and Pap test, all of which had been negative. This year, her Pap test revealed a low grade squamous intraepithelial lesion (LGSIL) and additionally a colposcopy was performed. Given the extent of the lesion and since the colposcopy was inadequate, the patient underwent a type 3 large loop excision of the transformation zone and a curettage of the endocervix under local anesthesia. The pathological diagnosis from cervical biopsy revealed an in situ adenocarcinoma of the endocervix with negative limits. The HPV subtypes 16 and 83 were detected with PCR. After proper consultation she decided to preserve her fertility and to undergo a regular follow-up, postponing hysterectomy after the completion of her family planning. In conclusion, this case report highlights the need for diagnostic surveillance regarding HPV-related cervical cancer even after vaccination.