This study aims to evaluate the frequency of microbial isolates and their susceptibility profiles cultured from clinical samples obtained from 26 simultaneous pancreas-kidney transplant (SPK) recipients suspected of infections during the early post-transplantation period.Data on microbiologic culture of 26 adult patients undergoing SPK were collected prospectively from 2001 to the end of 2006. Isolation and identification of cultured micro-organisms were performed according to standard microbiological procedures and commercially available tests. Susceptibility of the strains to antibacterial agents was made by the Clinical and Laboratory Standards Institute guidelines.All the patients were followed prospectively for the first 4 weeks after surgery. In total, 263 samples from clinical materials obtained from 26 SPK recipients were cultured. Bacterial cultures were positive in 29.3% (n = 77) clinical samples. Of these, 219 microbial strains were cultured. Gram-positive bacteria were found in 64% (n = 140), Gram-negative bacteria in 22.8% (n = 50), and fungal strains were isolated in 13.2% (n = 29). Incidence rate values for subsequent isolation of micro-organisms in the sub-periods of time for decreasing the SPK were Gram-positive bacteria (102.3–18.7; I versus IV), growing the Gram-negative bacteria (14–46.1 I versus III) IV were 14, decreasing to fungi (22.1–1.6, I versus IV). Until now this early post-transplantation period was considered homogeneous time after transplantation. This study shows that this period is actually heterogenous, with statistically significant differences being observed between results obtained in consecutive 4 weeks after transplantation.The results of this study show that the incidence rate was elevated with increasing age in the SPK group of patients. In the SPK group, our data showed the highest rate of isolation of micro-organisms compared with recipients of kidneys or liver.