Recent evidence has suggested that the formation of partially unfolded denatured intermediate serves as a crucial prerequisite for protein fibril formation/aggregation. Despite extensive exploration on amyloid fibril formation, the detailed molecular mechanism has remained largely unknown. Here, we examined the effects of urea on the denaturation of hen egg-white lysozymes. Our results demonstrated that, in the solutions (pH 7.4) with 8M urea at all temperatures and with 4M urea at 45 or 55 ℃, the amyloid fibril-like species were first produced and then vanished while such species were not observed under other conditions. In addition, SDS-PAGE results further indicated that larger aggregated species with less ordered structures were formed at the later stage of the urea-induced unfolding process owing to an unidentified conformational switch. We believe that the results in this work will aid in deciphering the molecular mechanism(s) of protein denaturation.