Dipylidium caninum is a common intestinal tapeworm of dogs, cats and foxes. However, it occasionally infects also humans. We present a case of D. caninum infection in a 2-year-old child living in the Subcarpathian province. The infection was asymptomatic in the first months. The symptoms of abdominal pains, sleep disorders, loss of appetite, hyperactivity and occasional slimy stools appeared later. Proglottids on the underwear, in water while bathing and mobile proglottids passed with the stool were also observed. Prior to appropriate diagnosis the child was treated with pyrantelum (Pyrantelum) and albendazolum (Zentel). However, proglottids were found again in the stool after a few days. We examined stool samples and perianal smears collected from the child and his family. The stool samples were tested by coproscopic methods. Direct methods (direct preparation in 0.9% sodium chloride and in Lugol's solution, Kato thick smear) and concentration methods (decantation with distilled water and Faust's zinc sulphate centrifugal flotation) were used. In the stool samples taken from the child, we observed D. caninum proglottids demonstrating lateral genital pores and many packets of eggs containing from one to a few, mostly 3 to 4 eggs. In the direct preparations in 0.9% sodium chloride and in Lugol's solution single packets with D. caninum eggs were detected. In decantation preparations many D. caninum egg packets were observed. It has to be reported that the child's mother was infected with Giardia intestinalis. Dipylidiasis in humans is a rarely encountered infection in Poland and the diagnosis may be difficult. For these reasons we reported clinical case presentation, diagnostics, treatment and epidemiology of D. caninum infection. We have shown that concentration methods such as decantation might be very helpful in the diagnosis of dipylidiasis.