Benzathine Penicillin G (BPG) is commonly used for treatment of penicillin-susceptible infections and secondary prevention of rheumatic fever. Death following administration of BPG is extremely rare-only a handful of cases have been described in the literature since the 1950's. In this case series from Israel and Switzerland, we describe nine cases of serious adverse reactions-six fatal reactions and three near-fatalities-occurring within minutes of receiving intramuscular BPG. Allergic reactions or faulty administration were not implicated in any of the cases; however, all patients had cardiac risk factors. This case series describes a relatively rare risk that should be borne in mind when prescribing BPG.