Blood samples from 15,426 blood donors from 17 out of Norway's 19 counties were tested for the presence of Kell (k) antigen. The K+ frequency in the total series was 8.28%, ranging from 4.61% in East-Agder county to 10.36% in Sogn and Fjordane. A1A2BO grouping of the donors showed that the lowest frequencies of group O were found in southeastern Norway (the counties surrounding the Oslo Fjord), and the highest along the coast of western Norway and in Nordland county. The highest A2 blood group frequencies were found in the three counties of northern Norway, with a maximum value in Finnmark county. The ratio between the genes determining the A1 and A2 properties (the p1/p2 ratio) was highest in southern Norway where in most counties was above 3. All the counties along the coast from Sogn and Fjordane northwards to the northern end of the country gave p1/p2 ratio below 3 and, in Finnmark, it was slightly below 2.