Prognosis of patients with undifferentiated gastric cancer is generally poor. The expression of various microRNAs (miRNAs) has not been comprehensively investigated in undifferentiated gastric cancer. Total RNA was extracted from the specimens of 42 undifferentiated gastric cancer tissues and paired normal gastric tissue. Quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) was performed for a set of 72 miRNAs. The expression of each miRNA relative to the internal control RNA was determined using the 2-DeltaCt method. The expression levels of 3 miRNAs (mir-34b, mir-34c and mir-128a) were significantly upregulated and those of 3 miRNAs (mir-128b, mir-129 and mir-148) were downregulated in undifferentiated gastric cancer tissue when compared with those of the paired normal tissues. The probability of survival was significantly lower in patients with high expression levels of mir-20b or 150. There was a correlation between mir-27a and lymph node metastasis. Our investigation provides a list of candidate miRNAs that may be associated with the prognosis in undifferentiated gastric cancer patients. Further study is warranted to identify the target genes of these miRNAs and their function.