Objective: To determine the frequency of mutations in exon 11 of the c-kit gene in patients with leukemia. Material and Methods: The study included 50 leukemia patients (31 with acute myeloid leukemia, 5 with acute lymphoblastic leukemia, 9 with chronic myeloid leukemia, and 5 with chronic lymphocytic leukemia) that underwent PCR-SSCP, followed by direct DNA sequencing. Results: In all, 28 of the leukemia patients were male and 22 were female, with a mean age of 31.88 years (range: 2-65 years). In total, 20 mutations in 19 patients were identified, including Lys550Asn, Tyr568Ser, Ile571Thr, Thr574Pro, Gln575His, Tyr578Pro, Asp579His, His580Gln, Arg586Thr, Asn587Asp, and Arg588Met, as well as novel point mutations at codons Ile563Lys, Val569Leu, Tyr570Ser, and Pro577Ser. Ile571Leu substitution was observed in 2 patients and Trp582Ser substitution was observed in 3 patients. Conclusion: The results suggest that mutations in exon 11 of the c-kit gene might be useful as molecular genetic markers for leukemia