Immunotherapy with intravesical bacillus Calmette-Guérin (BCG) is considered the most effective adjuvant to endoscopic resection of bladder urothelial carcinoma in the therapeutic management of non-muscle invasive (NMIBC) at intermediate and high risk of recurrence and progression (pTa - pT1 and high-grade carcinoma in situ, CIS). Despite its proven efficacy, this type of treatment can determine local and systemic side effects of moderate or severe gravity, with the histological diagnosis of epithelioid granulomas in different organs, even in the absence of microbiological positivity of BCG. The immunotherapy with BCG is usually well tolerated and the virulence of the attenuated BCG is very low in immuno-competent patients, although only 16% of patients are able to receive all the instillations of the maintenance period (3 years) of treatment provided by the protocols, precisely because of side effects. Minor side effects usually resolve within a few hours or days. They develop in 3-5% of patients and usually consist of local infectious complications. Manifestations of BCG dissemination, such as vascular and ocular complications, are much less common, while BCG-disseminated infections, with granulomatous pneumonia or hepatitis present, are quite rare, representing 0.5-2% of the complications recorded. We present the clinical case of granulomatous lung and possibly liver infection caused by BCG in a patient aged 56 years being treated for several weeks with intravesical BCG for NIMBC pT1 high grade associated with CIS.