This paper is the second in a series which sums up the results of an extensive project to quantify the duration-of-load (DOL) effect on different sized timber beams in different climates. The paper deals with straight (unnotched) beams. The results of various DOL-tests of stepwise and constant bending of M and glulam beams are reported and results of modelling outlined. It is concluded that in cyclically varying climate large cross-sections are less affected by the DOL-effect than smaller ones. The results do not show marked difference between M and glulam in susceptibility to the DOL-effect.