Colorectal carcinomas are characterized by multiple genetic aberrations that occur during tumorigenesis. Several tumor suppressor genes associated with colorectal carcinoma have been identified: MCC, APC, p53, nm23-H1, DCC, DPC4. We examined 73 cases of sporadic human colon cancer and corresponding normal tissue samples to evaluate the loss of heterozygosity (LOH) at the APC gene loci. The purpose of this study was also to evaluate whether the LOH at the APC gene is associated with clinicopathological characteristics in sporadic colon cancer. We also investigated presence and the frequency of the most common APC gene mutations and APC E1317Q and I1307K germ-line variants in Croatian colorectal cancer patients. Five markers in all patients were found to be heterozygous and informative for LOH analysis. LOH at the APC locus was detected in 30.1% of tumors were examined. The majority of APC gene LOH was observed in Dukes' B (55.6%) and in the moderately differentiated tumors (42.9%). Only 1309 APC gene mutation was detected in our samples. In one tumor sample, a new sporadic mutation of the APC gene in codon 1374 was detected. APC E1317Q and I1307K germ-line variants were not detected in our population. But APC E1317Q sporadic mutation was found in one tumor sample.