Abstract: The singular stress field of a transverse fillet weld toe is evaluated both analytically and numerically. A closed-form solution for the singular stress field is utilized for evaluating the stress intensity factor, K, of a crack emanating from the weld toe. The closed-form solution for the stress intensity factor is shown to be nearly identical with numerical results for two distinct crack paths. The closed-form solution provides new insight into the behaviour of the stress intensity factor for very short crack lengths, where much of the welded detail fatigue life is spent. The results have direct relevance to welded bridge details when assessing a cracked condition.