1088 single-nail tension tests were carried out on 109 spruce double-shear specimens in order to analyze variation of load-slip behaviour of non-predrilled nailed connections. The following load-slip parameters were determined from each test: maximum load, elastic slip modulus, initial slip modulus and slip modulus according to ISO 6891 as well as the three parameters of a function fitted to the load-slip relationship. Tests with nails penetrating a knot in the main or a side member resulted in a 20% increase in maximum load and elastic slip modulus. The autocorrelation of the parameters of the load-slip behaviour as well as their mutual correlation are independent of nail distance in the range of 73 mm to 657 mm.