A primary mucosa associated lymphoid tissue tumor (MALT) of the kidney in a 50-year-old man who suffered from on therapy resistant high blood pressure over 15 years period is presented. A mass in the right kidney (6x5x3 cm) during routine check up was discovered on ultrasonography and confirmed on CT scan and NMR. The patient was submitted to nephrectomy. A mass involving kidney, pyelon and upper part of the ureter was found. Histology showed low grade non-Hodgkin B-cell lymphoma of MALT type. The neoplastic cells were positive for monoclonal antibodies CD20, CD79alpha, surface and cytoplasmic and IgM immunoglobulins and showed light chain restriction (kappa+). After histology was available, a careful staging was performed. The disease was not found anywhere else. It was concluded that the patient belonged to the stage IE of primary kidney MALT lymphoma. Gastroscopy showed signs of chronic superficial gastritis. Urease test was positive and IgG antibodies against Helicobacter pylori in titer 421 were found as well. Except for Helicobacter pylori no additional therapy was given.