Alzheimer's disease (AD) related beta amyloid (Aβ) peptides possess high propensity towards aggregation. Their diffusion-controlled association follows a physico-chemically well-defined kinetics: the fibrillization starts from the monomeric/ dimeric state, and proceeds in the direction of oligomeric→protofibrillar→ fibrillar state producing neurotoxic aggregates. Nowadays one of the major directions of the drug design against AD is the synthesis of putative amyloid aggregation inhibitor molecules (AAI) which are able to hinder the formation of these toxic amyloid aggregates. Studies of both the Aβ aggregation and the effect of the AAIs on this process can be performed with several instrumental techniques. The size distribution of the aggregates up to the micron size range can be characterized with dynamic light scattering (DLS). On the other hand, species having a diameter above 5 nm can be visualized with transmission electron microscopy (TEM). In this work, we propose standardized sample preparation protocols in order to gain a reproducible aggregation profile of the Aβ peptides according to the experimental requirements. Besides, we investigate the effect of our formerly designed AAI, the RIIGLa pentapeptide on the aggregation of Aβ[1-42]. Based on our DLS and TEM results, we demonstrate the aggregation altering ability of this pentapeptide.