In the Federal Republic of Germany a BCG vaccine of strain Copenhagen 1331 is used. This vaccine was delivered with a content of 100,000 to 200,000 viable units per dose. Even in this small range one can see a relationship between spontaneously reported side effects, especially suppurated lymphadenitis in newborns. The lower the dosage the rarer the side effects. A diminution of viable units to a concentration of 100,000 to only 150,000 per dose shows a better compatibility though the conversion rate is still greater than 90%. Relevant side effects in schoolchildren or adults were not registered.