The effect of ionic strength on the interaction of ovalbumin, a globular egg white protein, in aqueous solution was investigated using static and dynamic light scattering. Strong repulsive interactions are observed at low ionic strength (3 mM). Aggregation of the proteins was induced by heating at low (3 mM) and high (100 mM) ionic strength as a function of the concentration. The size of the aggregates increases with increasing protein concentration and diverges close to the critical concentration for gelation, which is about 60 g/L at low ionic strength and 12 g/L at high ionic strength. Static and dynamic light scattering showed that at low ionic strength linear chains are formed with little branching until close to the gel point, while at high ionic strength denser branched aggregates are formed with a fractal dimension close to that found for other globular protein aggregates. The observations were confirmed by cryo-transmission electron microscopy. Heated systems at low ionic strength remained transparent and were studied in situ using static and dynamic light scattering. The relaxation of the concentration fluctuations occurs by cooperative diffusion, except when the gel point is approached and a slow secondary relaxation process is observed. The slow mode is attributed to the self-diffusion of the aggregates and restructuring of the system. The terminal relaxation time of the concentration fluctuations diverges in the neighborhood of the gel point because a fraction of the concentration fluctuations is progressively frozen in.