The protein contents of six Tarragona hazelnuts varieties were determined. The protein contents (g protein per 100 g hazelnuts) were between 12.1 g/100 g and 18.8 g/100 g, according to variety; a mean discrepancy of 2.3 g/100 g was detected between data from the same variety grown with irrigation and using a dry-farming method. Percentages of albumins, globulins, glutelins and prolamines were also determined. In all varieties albumins and globulins were the major fractions, averaging about 86.58% of the total protein content.