The authors review the results of the use of antibiotic prophylaxis (AP) during 412 cases of micro (MLC) and modern mini-laparotomy cholecystectomy (MMLC). 2 gr of Mandokef (M) or 1.5 gr of Zinacef (Z) were the employed antibiotics, administered intravenously 30 minutes before the commencement of the operations. In the case of patients above the age of 50 AP was given on routine basis. Apart from cases of obstructive cholecystitis (OC), a single shot of Mandokef or Zinacef proved effective; there was no occurrence of suppuration. Out of 94 under fifty patients--where in accordance with the accepted standpoint applied to traditional cholecystectomy AP would not have been necessary--AP was administered in 43 cases: no suppuration occurred. 51 patients did not receive AP; here 2 cases of suppuration occurred (4%). In 99 patients suffering from obstructive cholecystitis (OC), the single-shot AP was supplemented and continued with cover therapy where necessary. On the basis of the time elapsed between the presentation of the OC and the operation, the cases were classified in the following groups: 1.27 patients operated on within 10 days: no cases of suppuration or other complications II. 34 patients operated on between 10 days and 6 weeks: 2 cases (5.9%) III. 38 patients operated on after 6 weeks: 3 cases (7.9%) of suppuration or other complications were encountered. After MLC and MMLC the patients are emitted form hospital within 24-72 hours. However, 80% of the bacteria resoiling in the gallbladder can cause wound suppuration 4-10 days post-operatively.(ABSTRACT TRUNCATED AT 250 WORDS)